Sample records for wind turbine rotor

A windturbine has a rotor with at least one blade which has an aileron which is adjusted by an actuator. A hinge has two portions, one for mounting a stationary hinge arm to the blade, the other for coupling to the aileron actuator. Several types of hinges can be used, along with different actuators. The aileron is designed so that it has a constant chord with a number of identical sub-assemblies. The leading edge of the aileron has at least one curved portion so that the aileron does not vent over a certain range of angles, but vents if the position is outside the range. A cyclic actuator can be mounted to the aileron to adjust the position periodically. Generally, the aileron will be adjusted over a range related to the rotational position of the blade. A method for operating the cyclic assembly is also described.

A system and method for changing windturbinerotor diameters to meet changing wind speeds and control system loads is disclosed. The rotor blades on the windturbine are able to adjust length by extensions nested within or containing the base blade. The blades can have more than one extension in a variety of configurations. A cable winching system, a hydraulic system, a pneumatic system, inflatable or elastic extensions, and a spring-loaded jack knife deployment are some of the methods of adjustment. The extension is also protected from lightning by a grounding system.

A rotor hub is provided for coupling a windturbinerotor blade and a shaft. The hub has a yoke with a body which is connected to the shaft, and extension portions which are connected to teeter bearing blocks, each of which has an aperture. The blocks are connected to a saddle which envelops the rotor blade by one or two shafts which pass through the apertures in the bearing blocks. The saddle and blade are separated by a rubber interface which provides for distribution of stress over a larger portion of the blade. Two teeter control mechanisms, which may include hydraulic pistons and springs, are connected to the rotor blade and to the yoke at extension portions. These control mechanisms provide end-of-stroke damping, braking, and stiffness based on the teeter angle and speed of the blade.

A windturbine having a rotor, at least one rotor blade, and a plurality of generators, of which a first generator is configured to provide power to an electric grid and a second generator is configured to provide power to the windturbine during times of grid loss. The windturbine is configured to utilize power provided by the second generator to reduce loads on the windturbine during times of grid loss.

3.6MW Offshore Series WindTurbine GE Energy #12;Feature Variable Hub heights & rotor diameters-savings feature, considering the rigors of offshore power generation. The 3.6 MW offshore windturbine also, for both on and offshore use. Special features include... As the world's first commercially available wind

A reduction in cost of energy from wind is anticipated when maximum allowable tip velocity is allowed to increase. Rotor torque decreases as tip velocity increases and rotor size and power rating are held constant. Reduction in rotor torque yields a lighter weight gearbox, a decrease in the turbine cost, and an increase in the capacity for the turbine to deliver cost competitive electricity. The high speed rotor incurs costs attributable to rotor aero-acoustics and system loads. The increased loads of high speed rotors drive the sizing and cost of other components in the system. Rotor, drivetrain, and tower designs at 80 m/s maximum tip velocity and 100 m/s maximum tip velocity are created to quantify these effects. Component costs, annualized energy production, and cost of energy are computed for each design to quantify the change in overall cost of energy resulting from the increase in turbine tip velocity. High fidelity physics based models rather than cost and scaling models are used to perform the work. Results provide a quantitative assessment of anticipated costs and benefits for high speed rotors. Finally, important lessons regarding full system optimization of windturbines are documented.

A method of manufacturing a root portion of a windturbine blade includes, in an exemplary embodiment, providing an outer layer of reinforcing fibers including at least two woven mats of reinforcing fibers, providing an inner layer of reinforcing fibers including at least two woven mats of reinforcing fibers, and positioning at least two bands of reinforcing fibers between the inner and outer layers, with each band of reinforcing fibers including at least two woven mats of reinforcing fibers. The method further includes positioning a mat of randomly arranged reinforcing fibers between each pair of adjacent bands of reinforcing fibers, introducing a polymeric resin into the root potion of the windturbine blade, infusing the resin through the outer layer, the inner layer, each band of reinforcing fibers, and each mat of random reinforcing fibers, and curing the resin to form the root portion of the windturbine blade.

DETECTION OF IMPULSE-LIKE AIRBORNE SOUND FOR DAMAGE IDENTIFICATION IN ROTOR BLADES OF WINDTURBINES burdens of windturbines. To detect damage of rotor blades, several research projects focus on an acoustic, rotor blade, windturbine INTRODUCTION There are several publications of non destructive damage

We examine the operating modes of a two-bladed teetered windturbine. Because of the gyroscopic asymmetry of its rotor, this turbine's dynamics can be quite distinct from those of a turbine with three or more blades. This asymmetry leads to system equations with periodic coefficients that are solved using the Floquet approach to extract the correct modal parameters. The system equations are derived using a simple analytical model with four degrees of freedom: cacelle yaw, rotor teeter, and flapping associated with each blade. Results confirm that the turbine modes become more dominated by the centrifugal and gyroscopic effects as the rotor speed increases. They gyroscopic effect may also cause dynamic instability. Under certain design conditions, yaw and teeter modal frequencies may coalesce.

Sparkær Blade Test Centre Windturbines with a rotor diameter exceed- ing 2 metres must have a type of a windturbine. Failure of a rotor blade in service often involves damage of the entire turbine operating type cer- tification systems for windturbines. Reg. no. 427 The Sparkær Blade Test Centre became

Numerical Investigation of a WindTurbineRotor with an aerodynamically redesigned hub-region J methods on a redesigned modern Mega-Watt sized windturbine, where the new design includes an increase of the blade in the vicinity of the windturbine nacelle, to obtain an aerodynamically more efficient rotor

RIS0-M-2432 SIMPLIFIED LAWS OF SIMIALRITY FOR WINDTURBINEROTORS Helge Petersen The Test Station for Small Windmills Abstract, Laws of similarity or scaling laws for the character- istics of a windturbinerotor are of importance to the designer even during the initial design phase of a new windturbine con

A spar cap for a windturbinerotor blade. The spar cap may include multiple preform components. The multiple preform components may be planar sheets having a swept shape with a first end and a second end. The multiple preform components may be joined by mating the first end of a first preform component to the second end of a next preform component, forming the spar cap.

Wind-driven power systems is a renewable energy technology that is still in the early stages of development. Wind power plants installed in early 1980s suffered structural failures chiefly because of incomplete understanding of wind forces (turbulent), in some cases because of poor product quality. Failures of rotor blades are now somewhat better understood. This committee has examined the experience base accumulated by windturbines and the R and D programs sponsored by DOE. It is concluded that a wind energy system such as is described is within the capability of engineering practice; however because of certain gaps in knowledge, and the presence of only one major integrated manufacturer of wind power machines in the USA, a DOE R and D investment is still required.

problems such as helicopter rotors and propellers. In particular, windturbine blades can experience large from the tower support on downwind, horizontal axis windturbines. These blade/inflow/tower wake in large scale windturbines, because the blade passage frequency is well below the audible range

A method for reducing load and providing yaw alignment in a windturbine includes measuring displacements or moments resulting from asymmetric loads on the windturbine. These measured displacements or moments are used to determine a pitch for each rotor blade to reduce or counter asymmetric rotor loading and a favorable yaw orientation to reduce pitch activity. Yaw alignment of the windturbine is adjusted in accordance with the favorable yaw orientation and the pitch of each rotor blade is adjusted in accordance with the determined pitch to reduce or counter asymmetric rotor loading.

This report presents the results of the turbinerotor study completed by Global Energy Concepts (GEC) as part of the U.S. Department of Energy's WindPACT (Wind Partnership for Advanced Component Technologies) project. The purpose of the WindPACT project is to identify technology improvements that will enable the cost of energy from windturbines to fall to a target of 3.0 cents/kilowatt-hour in low wind speed sites. The study focused on different rotor configurations and the effect of scale on those rotors.

Multi-megawatt utility-scale windturbines operate in a turbulent, thermally-driven atmosphere where wind speed and air temperature vary with height. Turbines convert the wind's momentum into electrical power, and so changes in the atmosphere across the rotor disk influence the power produced by the turbine. To characterize the inflow into utility scale turbines at the National Wind Technology Center (NWTC) near Boulder, Colorado, NREL recently built two 135-meter inflow monitoring towers. This poster introduces the towers and the measurements that are made, showing some of the data obtained in the first few months of operation in 2011.

The effects of modifying the inboard portion of the NREL Phase VI rotor using a thickened, flatback version of the S809 design airfoil are studied using a three-dimensional Reynolds-averaged Navier-Stokes method. A motivation for using such a thicker airfoil design coupled with a blunt trailing edge is to alleviate structural constraints while reducing blade weight and maintaining the power performance of the rotor. The calculated results for the baseline Phase VI rotor are benchmarked against wind tunnel results obtained at 10, 7, and 5 meters per second. The calculated results for the modified rotor are compared against those of the baseline rotor. The results of this study demonstrate that a thick, flatback blade profile is viable as a bridge to connect structural requirements with aerodynamic performance in designing future windturbinerotors.

A multisection blade for a windturbine includes a hub extender having a pitch bearing at one end, a skirt or fairing having a hole therethrough and configured to mount over the hub extender, and an outboard section configured to couple to the pitch bearing.

There has been invented a turbine engine with a single rotor which cools the engine, functions as a radial compressor, pushes air through the engine to the ignition point, and acts as an axial turbine for powering the compressor. The invention engine is designed to use a simple scheme of conventional passage shapes to provide both a radial and axial flow pattern through the single rotor, thereby allowing the radial intake air flow to cool the turbine blades and turbine exhaust gases in an axial flow to be used for energy transfer. In an alternative embodiment, an electric generator is incorporated in the engine to specifically adapt the invention for power generation. Magnets are embedded in the exhaust face of the single rotor proximate to a ring of stationary magnetic cores with windings to provide for the generation of electricity. In this alternative embodiment, the turbine is a radial inflow turbine rather than an axial turbine as used in the first embodiment. Radial inflow passages of conventional design are interleaved with radial compressor passages to allow the intake air to cool the turbine blades.

of the rotor of a windturbine and the rated power of a permanent magnet synchronous machine. This is made of the windturbine, the gearbox's transformation ratio, the battery voltage and the wind speed probability's rated power and the windturbine's rotor size. The system studied in this paper consists of 220 (V)/50

When extracting energy from the wind using horizontal-axis upwind windturbines, a primary condition for maximum power yield is the ability to align the rotor axis with the dominating wind direction. Attempts have been made to improve yaw alignment by applying advanced measurement techniques such as LIDARs. This study is focused at assessing the current performance of an operating turbine and exploring how the yaw alignment can be improved using existing measurements. By analyzing available turbine and met mast data a correction scheme for the original yaw alignment system is synthesized. The correction scheme is applied and it is seen that with the correction scheme in place, the power yield below rated is raised 1-5 percent. Furthermore, results indicate that blade load variations are decreased when the correction scheme is applied. The results are associated with uncertainties due to the amount of available data and the wind site climate. Further work should be focused at gathering more experimental data.

A rotor for use in turbine applications has a centrifugal compressor having axially disposed spaced apart fins forming passages and an axial turbine having hollow turbine blades interleaved with the fins and through which fluid from the centrifugal compressor flows.

To alleviate the mass-scaling issues associated with conventional upwind rotors of extreme-scale turbines, a downwind rotor concept is proposed which employs fixed blade curvature based on force alignment at rated conditions. For a given peak stress constraint, the reduction in downwind cantilever loads allows reduced shell and spar thickness, and thus a reduced blade mass as compared with a conventional upwind rotor, especially as rotor sizes approach extreme-scales. To quantify this mass reduction, a Finite Element Analysis was conducted for a 10 MW rated rotor based on the NREL offshore 5 MW baseline windturbine. The results show that this 'pre-alignment' yields a net downstream deflection of 32 deg, a downward hub-pitch angle of 6 deg, a 20% increase in blade length (to maintain the same radius as the conventional blade), and a net mass savings of about 50% through decreased shell and spar thicknesses. The pre-alignment may also allow a more straightforward and efficient segmentation of the blade since shear stresses near joints are substantially reduced. Segmenting, in turn, can dramatically reduce costs associated with fabrication, transport and assembly for extreme-scale off-shore systems. The pre-aligned geometric curvature can also help alleviate tower wake effects on the blades since blade tips (where shadow effects can be most problematic) are shifted downstream where the tower wake is weaker. In addition, the portion of the tower that is upstream of the blade tips can be faired with an externally-rotating aerodynamic shroud. Furthermore, the downwind rotor can allow a floating off-shore tri-pod platform to reduce tower weight and yaw-control requirements. A simple economic analysis of the segmented ultralight pre-aligned rotor (SUPAR) concept suggests that the overall system cost savings can be as much as 25%, indicating that more detailed (numerical and experimental) investigations are warranted.

Measured and predicted rotor performance for the SERI advanced windturbine blades were compared to assess the accuracy of predictions and to identify the sources of error affecting both predictions and measurements. An awareness of these sources of error contributes to improved prediction and measurement methods that will ultimately benefit future rotor design efforts. Propeller/vane anemometers were found to underestimate the wind speed in turbulent environments such as the San Gorgonio Pass wind farm area. Using sonic or cup anemometers, good agreement was achieved between predicted and measured power output for wind speeds up to 8 m/sec. At higher wind speeds an optimistic predicted power output and the occurrence of peak power at wind speeds lower than measurements resulted from the omission of turbulence and yaw error. In addition, accurate two-dimensional (2-D) airfoil data prior to stall and a post stall airfoil data synthesization method that reflects three-dimensional (3-D) effects were found to be essential for accurate performance prediction. 11 refs.

A windturbine of the type having an airfoil blade (15) mounted on a flexible beam (20) and a pitch governor (55) which selectively, torsionally twists the flexible beam in response to windturbine speed thereby setting blade pitch, is provided with a limiter (85) which restricts unwanted pitch change at operating speeds due to torsional creep of the flexible beam. The limiter allows twisting of the beam by the governor under excessive wind velocity conditions to orient the blades in stall pitch positions, thereby preventing overspeed operation of the turbine. In the preferred embodiment, the pitch governor comprises a pendulum (65,70) which responds to changing rotor speed by pivotal movement, the limiter comprising a resilient member (90) which engages an end of the pendulum to restrict further movement thereof, and in turn restrict beam creep and unwanted blade pitch misadjustment.

A windturbine includes a rotor having a hub and at least one blade having a torsionally rigid root, an inboard section, and an outboard section. The inboard section has a forward sweep relative to an elastic axis of the blade and the outboard section has an aft sweep.

A windturbine includes a rotor having a hub and at least one blade having a torsionally rigid root, an inboard section, and an outboard section. The inboard section has a forward sweep relative to an elastic axis of the blade and the outboard section has an aft sweep.

Estimation of Wind Speed in Connection to a WindTurbine X. Ma #3; , N. K. Poulsen #3; , H. Bindner y December 20, 1995 Abstract The wind speed varies over the rotor plane of windturbine making the wind speed on the rotor plane will be estimated by using a windturbine as a wind measuring device

A method for braking a windturbine including at least one rotor blade coupled to a rotor. The method includes selectively controlling an angle of pitch of the at least one rotor blade with respect to a wind direction based on a design parameter of a component of the windturbine to facilitate reducing a force induced into the windturbine component as a result of braking.

An aerodynamic spoiler system for a vertical axis windturbine includes spoilers on the blades initially stored near the rotor axis to minimize drag. A solenoid latch adjacent the central support tower releases the spoilers and centrifugal force causes the spoilers to move up the turbine blades away from the rotor axis, thereby producing a braking effect and actual slowing of the associated windturbine, if desired. The spoiler system can also be used as an infinitely variable power control by regulated movement of the spoilers on the blades over the range between the undeployed and fully deployed positions. This is done by the use of a suitable powered reel and cable located at the rotor tower to move the spoilers.

A windturbine comprising an electrical generator that includes a rotor assembly. A windrotor that includes a windrotor hub is directly coupled to the rotor assembly via a simplified connection. The windrotor and generator rotor assembly are rotatably mounted on a central spindle via a bearing assembly. The windrotor hub includes an opening having a diameter larger than the outside diameter of the central spindle adjacent the bearing assembly so as to allow access to the bearing assembly from a cavity inside the windrotor hub. The spindle is attached to a turret supported by a tower. Each of the spindle, turret and tower has an interior cavity that permits personnel to traverse therethrough to the cavity of the windrotor hub. The windturbine further includes a frictional braking system for slowing, stopping or keeping stopped the rotation of the windrotor and rotor assembly.

A windturbine comprising an electrical generator that includes a rotor assembly. A windrotor that includes a windrotor hub is directly coupled to the rotor assembly via a simplified connection. The windrotor and generator rotor assembly are rotatably mounted on a central spindle via a bearing assembly. The windrotor hub includes an opening having a diameter larger than the outside diameter of the central spindle adjacent the bearing assembly so as to allow access to the bearing assembly from a cavity inside the windrotor hub. The spindle is attached to a turret supported by a tower. Each of the spindle, turret and tower has an interior cavity that permits personnel to traverse therethrough to the cavity of the windrotor hub. The windturbine further includes a frictional braking system for slowing, stopping or keeping stopped the rotation of the windrotor and rotor assembly.

Broad Funding Opportunity Announcement Project: FloDesign WindTurbines innovative windturbine, inspired by the design of jet engines, could deliver 300% more power than existing windturbines of the same rotor diameter by extracting more energy over a larger area. FloDesign WindTurbines unique shrouded design expands the wind capture area, and the mixing vortex downstream allows more energy to flow through the rotor without stalling the turbine. The unique rotor and shrouded design also provide significant opportunity for mass production and simplified assembly, enabling mid-scale turbines (approximately 100 kW) to produce power at a cost that is comparable to larger-scale conventional turbines.

Due to catastrophic damage, the turbine-compressor rotor of a gas turbine has been bent 0.62 mm. The in-situ repair process of rotor straightening is fully described. The repair process included the design of special fixtures for placing the rotor vertically and then hydraulically tensioning the rotor bolts for discs disassembling and run-out check by a special rotary equipment. After the repair process the rotor run-out fell within the design limits. Finally the rotor was put back into service. The approach to the in-house repair of the rotor bend has been successful and can be widely recommended for users of turbomachinery.

A rotor for use in turbine applications has a radial compressor/pump having radially disposed spaced apart fins forming passages and a radial turbine having hollow turbine blades interleaved with the fins and through which fluid from the radial compressor/pump flows. The rotor can, in some applications, be used to produce electrical power.

A multiple piece turbinerotor blade with a shell having an airfoil shape and secured between a spar and a platform with the spar including a tip end piece. a snap ring fits around the spar and abuts against the spar tip end piece on a top side and abuts against a shell on the bottom side so that the centrifugal loads from the shell is passed through the snap ring and into the spar and not through a tip cap dovetail slot and projection structure.

This CRADA was developed as a funds-in CRADA with DeWind to assess the suitability of facilities and equipment at the NWTC for performing certification blade testing on windturbine blades made from advanced materials. DeWind produces a windturbine blade which includes the use of high-strength and stiffness materials. NREL and DeWind had a mutual interest in defining the necessary facilities, equipment, and test methods for testing large windturbine blades which incorporate advanced materials and adaptive structures, as the demands on test equipment and infrastructure are greater than current capabilities. Work under this CRADA would enable DeWind to verify domestic capability for certification-class static and fatigue testing, while NREL would be able to identify and develop specialized test capabilities based on the test requirements.

Operations and maintenance costs for offshore wind plants are significantly higher than the current costs for land-based (onshore) wind plants. One way to reduce these costs would be to implement a structural health and prognostic management (SHPM) system as part of a condition based maintenance paradigm with smart load management and utilize a state-based cost model to assess the economics associated with use of the SHPM system. To facilitate the development of such a system a multi-scale modeling approach developed in prior work is used to identify how the underlying physics of the system are affected by the presence of damage and faults, and how these changes manifest themselves in the operational response of a full turbine. This methodology was used to investigate two case studies: (1) the effects of rotor imbalance due to pitch error (aerodynamic imbalance) and mass imbalance and (2) disbond of the shear web; both on a 5-MW offshore windturbine in the present report. Based on simulations of damage in the turbine model, the operational measurements that demonstrated the highest sensitivity to the damage/faults were the blade tip accelerations and local pitching moments for both imbalance and shear web disbond. The initial cost model provided a great deal of insight into the estimated savings in operations and maintenance costs due to the implementation of an effective SHPM system. The integration of the health monitoring information and O&M cost versus damage/fault severity information provides the initial steps to identify processes to reduce operations and maintenance costs for an offshore wind farm while increasing turbine availability, revenue, and overall profit.

In a windturbine (104, 500, 704) having a plurality of blades (132, 404, 516, 744) and a blade rotor hub (120, 712), a lightning protection system (100, 504, 700) for conducting lightning strikes to any one of the blades and the region surrounding the blade hub along a path around the blade hub and critical components of the windturbine, such as the generator (112, 716), gearbox (708) and main turbine bearings (176, 724).

WindTurbine Competition Introduction: The Society of Hispanic Professional Engineers, SHPE at UTK, wishes to invite you to participate in our first `WindTurbine' competition as part of Engineer's Week). You will be evaluated by how much power your windturbine generates at the medium setting of our fan

to the design of a windturbinerotor. Number of blades The number of blades does not have a significant impact on the efficiency of a windturbine. We have chosen a two blade design because of ease of fabrication in order) (2) · This two blade micro windturbine meets the optimal specifications to ensure good efficiency

Greater efficiency in windturbine systems is achieved by allowing the rotor to change its rate of rotation as the wind speed changes. The windturbine system is decoupled from the utility grid and a variable speed operation ...

A windturbine generator includes a stator having a core and a plurality of stator windings circumferentially spaced about a generator longitudinal axis. A rotor is rotatable about the generator longitudinal axis, and the rotor includes a plurality of magnetic elements coupled to the rotor and cooperating with the stator windings. The magnetic elements are configured to generate a magnetic field and the stator windings are configured to interact with the magnetic field to generate a voltage in the stator windings. A heat pipe assembly thermally engaging one of the stator and the rotor to dissipate heat generated in the stator or rotor.

A method for controlling a windturbine having twist bend coupled rotor blades on a rotor mechanically coupled to a generator includes determining a speed of a rotor blade tip of the windturbine, measuring a current twist distribution and current blade loading, and adjusting a torque of a generator to change the speed of the rotor blade tip to thereby increase an energy capture power coefficient of the windturbine.

Ames Laboratory associate scientist Gene Takle talks about research into the effect of windturbines on nearby crops. Preliminary results show the turbines may have a positive effect by cooling and drying the crops and assisting with carbon dioxide uptake.

Ames Laboratory associate scientist Gene Takle talks about research into the effect of windturbines on nearby crops. Preliminary results show the turbines may have a positive effect by cooling and drying the crops and assisting with carbon dioxide uptake.

A windturbine (100) comprising an electrical generator (108) that includes a rotor assembly (112). A windrotor (104) that includes a windrotor hub (124) is directly coupled to the rotor assembly via a simplified connection. The windrotor and generator rotor assembly are rotatably mounted on a central spindle (160) via a bearing assembly (180). The windrotor hub includes an opening (244) having a diameter larger than the outside diameter of the central spindle adjacent the bearing assembly so as to allow access to the bearing assembly from a cavity (380) inside the windrotor hub. The spindle is attached to a turret (140) supported by a tower (136). Each of the spindle, turret and tower has an interior cavity (172, 176, 368) that permits personnel to traverse therethrough to the cavity of the windrotor hub. The windturbine further includes a frictional braking system (276) for slowing, stopping or keeping stopped the rotation of the windrotor and rotor assembly.

A method and apparatus for improving windturbine performance by alleviating loads and controlling the rotor. The invention employs the use of a passively adaptive blade that senses the wind velocity or rotational speed, and accordingly modifies its aerodynamic configuration. The invention exploits the load mitigation prospects of a blade that twists toward feather as it bends. The invention includes passively adaptive windturbinerotors or blades with currently preferred power control features. The apparatus is a composite fiber horizontal axis wind-turbine blade, in which a substantial majority of fibers in the blade skin are inclined at angles of between 15 and 30 degrees to the axis of the blade, to produces passive adaptive aeroelastic tailoring (bend-twist coupling) to alleviate loading without unduly jeopardizing performance.

A method and apparatus for improving windturbine performance by alleviating loads and controlling the rotor. The invention employs the use of a passively adaptive blade that senses the wind velocity or rotational speed, and accordingly modifies its aerodynamic configuration. The invention exploits the load mitigation prospects of a blade that twists toward feather as it bends. The invention includes passively adaptive windturbinerotors or blades with currently preferred power control features. The apparatus is a composite fiber horizontal axis wind-turbine blade, in which a substantial majority of fibers in the blade skin are inclined at angles of between 15 and 30 degrees to the axis of the blade, to produces passive adaptive aeroelastic tailoring (bend-twist coupling) to alleviate loading without unduly jeopardizing performance.

This report provides an overview on the current state of windturbine control and introduces a number of active techniques that could be potentially used for control of windturbine blades. The focus is on research regarding active flow control (AFC) as it applies to windturbine performance and loads. The techniques and concepts described here are often described as 'smart structures' or 'smart rotor control'. This field is rapidly growing and there are numerous concepts currently being investigated around the world; some concepts already are focused on the wind energy industry and others are intended for use in other fields, but have the potential for windturbine control. An AFC system can be broken into three categories: controls and sensors, actuators and devices, and the flow phenomena. This report focuses on the research involved with the actuators and devices and the generated flow phenomena caused by each device.

The North Wind 250 windturbine is under development at Northern Power Systems (NPS) in Moretown, VT. The turbine uses a unique, flow-through, teetered-rotor design. This design eliminates structural discontinuities at the blade/hub interface by fabricating the rotor as one continuous structural element. To accomplish this, the two blade spars are joined at the center of the rotor using a proprietary bonding technique. Fatigue tests were conducted on the full-scale rotor joint at the National Renewable Energy Laboratory (NREL). Subsequent tests are now underway to test the full-scale rotor and hub assembly to verify the design assumptions. The test articles were mounted in dedicated test fixtures. For the joint test, a constant moment was generated across the joint and parent material. Hydraulic actuators applied sinusoidal loading to the test article at levels equivalent to 90% of the extreme wind load for over one million cycles. When the loading was increased to 112% of the extreme wind load, the joint failed by buckling. Strain levels were monitored at 14 locations inside and outside of the blade joint during the test. The tests were used to qualify this critical element of the rotor for field testing and to provide information needed to improve the structural design of the joint.

In the present study, a numerical simulation tool has been developed for the rotor-floater-tether coupled dynamic analysis of Multiple Unit Floating Offshore WindTurbine (MUFOWT) in the time domain including aero-blade-tower dynamics and control...

In the present study, a numerical simulation tool has been developed for the rotor-floater-tether coupled dynamic analysis of Multiple Unit Floating Offshore WindTurbine (MUFOWT) in the time domain including aero-blade-tower dynamics and control...

A windturbine comprising an electrical generator that includes a rotor assembly. A windrotor that includes a windrotor hub is directly coupled to the rotor assembly via a simplified connection. The windrotor and generator rotor assembly are rotatably mounted on a central spindle via a bearing assembly. The windrotor hub includes an opening having a diameter larger than the outside diameter of the central spindle adjacent the bearing assembly so as to allow access to the bearing assembly from a cavity inside the windrotor hub. The spindle is attached to a turret supported by a tower. Each of the spindle, turret and tower has an interior cavity that permits personnel to traverse therethrough to the cavity of the windrotor hub. The windturbine further includes a frictional braking system for slowing, stopping or keeping stopped the rotation of the windrotor and rotor assembly.

A windturbine is provided that minimizes the size of the drive train and nacelle while maintaining the power electronics and transformer at the top of the tower. The turbine includes a direct drive generator having an integrated disk brake positioned radially inside the stator while minimizing the potential for contamination. The turbine further includes a means for mounting a transformer below the nacelle within the tower.

A windturbine is provided that minimizes the size of the drive train and nacelle while maintaining the power electronics and transformer at the top of the tower. The turbine includes a direct drive generator having an integrated disk brake positioned radially inside the stator while minimizing the potential for contamination. The turbine further includes a means for mounting a transformer below the nacelle within the tower.

A windturbine is provided that minimizes the size of the drive train and nacelle while maintaining the power electronics and transformer at the top of the tower. The turbine includes a direct drive generator having an integrated disk brake positioned radially inside the stator while minimizing the potential for contamination. The turbine further includes a means for mounting a transformer below the nacelle within the tower.

A windturbine is provided that minimizes the size of the drive train and nacelle while maintaining the power electronics and transformer at the top of the tower. The turbine includes a direct drive generator having an integrated disk brake positioned radially inside the stator while minimizing the potential for contamination. The turbine further includes a means for mounting a transformer below the nacelle within the tower.

A tip shroud that includes a plurality of damping fins, each damping fin including a substantially non-radially-aligned surface that is configured to make contact with a tip shroud of a neighboring rotor blade. At least one damping fin may include a leading edge damping fin and at least one damping fin may include a trailing edge damping fin. The leading edge damping fin may be configured to correspond to the trailing edge damping fin.

A vertical axis windturbine is described. The windturbine can include a top ring, a middle ring and a lower ring, wherein a plurality of vertical airfoils are disposed between the rings. For example, three vertical airfoils can be attached between the upper ring and the middle ring. In addition, three more vertical airfoils can be attached between the lower ring and the middle ring. When wind contacts the vertically arranged airfoils the rings begin to spin. By connecting the rings to a center pole which spins an alternator, electricity can be generated from wind.

Methods and apparatus for assembling a windturbine generator are provided. The windturbine generator includes a core and a plurality of stator windings circumferentially spaced about a generator longitudinal axis, a rotor rotatable about the generator longitudinal axis wherein the rotor includes a plurality of magnetic elements coupled to a radially outer periphery of the rotor such that an airgap is defined between the stator windings and the magnetic elements and the plurality of magnetic elements including a radially inner periphery having a first diameter. The windturbine generator also includes a bearing including a first member in rotatable engagement with a radially inner second member, the first member including a radially outer periphery, a diameter of the radially outer periphery of the first member being substantially equal to the first diameter, the rotor coupled to the stator through the bearing such that a substantially uniform airgap is maintained.

WindTurbine Blockset in Saber General Overview and Description of the Models Florin Iov, Adrian Turbine Blockset in Saber Abstract. This report presents a new developed Saber Toolbox for windturbine, optimize and design windturbines". The report provides a quick overview of the Saber and then explains

The project objective was to optimize the performance of the Hi-Q Rotor. Early research funded by the California Energy Commission indicated the design might be advantageous over state-of-the-art turbines for collecting wind energy in low wind conditions. The Hi-Q Rotor is a new kind of rotor targeted for harvesting wind in Class 2, 3, and 4 sites, and has application in areas that are closer to cities, or 'load centers.' An advantage of the Hi-Q Rotor is that the rotor has non-conventional blade tips, producing less turbulence, and is quieter than standard windturbine blades which is critical to the low-wind populated urban sites. Unlike state-of-the-art propeller type blades, the Hi-Q Rotor has six blades connected by end caps. In this phase of the research funded by DOE's Inventions and Innovation Program, the goal was to improve the current design by building a series of theoretical and numeric models, and composite prototypes to determine a best of class device. Development of the rotor was performed by aeronautical engineering and design firm, DARcorporation. From this investigation, an optimized design was determined and an 8-foot diameter, full-scale rotor was built and mounted using a Bergey LX-1 generator and furling system which were adapted to support the rotor. The Hi-Q Rotor was then tested side-by-side against the state-of-the-art Bergey XL-1 at the Alternative Energy Institute's Wind Test Center at West Texas State University for six weeks, and real time measurements of power generated were collected and compared. Early wind tunnel testing showed that the cut-in-speed of the Hi-Q rotor is much lower than a conventional tested HAWT enabling the Hi-Q WindTurbine to begin collecting energy before a conventional HAWT has started spinning. Also, torque at low wind speeds for the Hi-Q WindTurbine is higher than the tested conventional HAWT and enabled the windturbine to generate power at lower wind speeds. Based on the data collected, the results of our first full-scale prototype windturbine proved that higher energy can be captured at lower wind speeds with the new Hi-Q Rotor. The Hi-Q Rotor is almost 15% more productive than the Bergey from 6 m/s to 8 m/s, making it ideal in Class 3, 4, and 5 wind sites and has application in the critical and heretofore untapped areas that are closer to cities, 'load centers,' and may even be used directly in urban areas. The additional advantage of the Hi-Q Rotor's non-conventional blade tips, which eliminates most air turbulence, is noise reduction which makes it doubly ideal for populated urban areas. Hi-Q Products recommends one final stage of development to take the Hi-Q Rotor through Technology Readiness Levels 8-9. During this stage of development, the rotor will be redesigned to further increase efficiency, match the rotor to a more suitable generator, and lower the cost of manufacturing by redesigning the structure to allow for production in larger quantities at lower cost. Before taking the rotor to market and commercialization, it is necessary to further optimize the performance by finding a better generator and autofurling system, ones more suitable for lower wind speeds and rpms should be used in all future testing. The potential impact of this fully developed technology will be the expansion and proliferation of energy renewal into the heretofore untapped Class 2, 3, 4, and 5 Wind Sites, or the large underutilized sites where the wind speed is broken by physical features such as mountains, buildings, and trees. Market estimates by 2011, if low wind speed technology can be developed are well above: 13 million homes, 675,000 commercial buildings, 250,000 public facilities. Estimated commercial exploitation of the Hi-Q Rotor show potential increase in U.S. energy gained through the clean, renewable wind energy found in low and very low wind speed sites. This new energy source would greatly impact greenhouse emissions as well as the public sector's growing energy demands.

Optimization of WindTurbine Operation by Use of Spinner Anemometer TF Pedersen, NN SÃ¸rensen, L Title: Optimization of WindTurbine Operation by Use of Spinner Anemometer Department: Wind Energy prototype windturbine. Statistics of the yaw error showed an average of about 10Â°. The average flow

Due to swish and thump amplitude modulation, the noise of windturbines cause more annoyance than other environmental noise of the same average level. The wind shear accounts for the thump modulation (van den Berg effect). Making use of the wind speed measurements at the hub height, as well as at the top and the bottom of the rotor disc (Fig.1), the non-standard wind profile is applied. It causes variations in the A-weighted sound pressure level, LpA. The difference between the maximum and minimum of LpA characterizes thump modulation (Fig.2).

The D-lab Honduras team designed and constructed a wind-powered water pump in rural Honduras during IAP 2007. Currently, the system does not work under its own power and water must be pumped by hand. This thesis seeks to ...

Model Predictive Control of WindTurbines Martin Klauco Kongens Lyngby 2012 IMM-MSc-2012-65 #12;Summary Windturbines are the biggest part of the green energy industry. Increasing interest control strategies. Control strategy has a significant impact on the windturbine operation on many levels

A feasibility study of windturbine blade surface crack detection using an optical inspection technique was investigated to assess its ability to detect surface flaws on an on-tower windturbine blade and investors. Rotor blades are one of the largest mechanical components of a windturbine and cannot

Numerical Analysis of Winglets on WindTurbine Blades using CFD Jeppe Johansen and Niels N of adding a winglet to a windturbinerotor is to decrease the total drag from the blades and thereby increase. The resulting pressure difference on an operating windturbine blade causes inward spanwise flow

Broad Funding Opportunity Announcement Project: Makani Power is developing an Airborne WindTurbine (AWT) that eliminates 90% of the mass of a conventional windturbine and accesses a stronger, more consistent wind at altitudes of near 1,000 feet. At these altitudes, 85% of the country can offer viable wind resources compared to only 15% accessible with current technology. Additionally, the Makani Power wing can be economically deployed in deep offshore waters, opening up a resource which is 4 times greater than the entire U.S. electrical generation capacity. Makani Power has demonstrated the core technology, including autonomous launch, land, and power generation with an 8 meter wingspan, 20 kW prototype. At commercial scale, Makani Power aims to develop a 600 kW, 28 meter wingspan product capable of delivering energy at an unsubsidized cost competitive with coal, the current benchmark for low-cost power.

A tornado type windturbine has a vertically disposed wind collecting tower with spaced apart inner and outer walls and a central bore. The upper end of the tower is open while the lower end of the structure is in communication with a wind intake chamber. An opening in the wind chamber is positioned over a turbine which is in driving communication with an electrical generator. An opening between the inner and outer walls at the lower end of the tower permits radially flowing air to enter the space between the inner and outer walls while a vertically disposed opening in the wind collecting tower permits tangentially flowing air to enter the central bore. A porous portion of the inner wall permits the radially flowing air to interact with the tangentially flowing air so as to create an intensified vortex flow which exits out of the top opening of the tower so as to create a low pressure core and thus draw air through the opening of the wind intake chamber so as to drive the turbine.

A windturbine includes a yaw spring return assembly to return the nacelle from a position to which it has been rotated by yawing forces, thus preventing excessive twisting of the power cables and control cables. It also includes negative coning restrainers to limit the bending of the flexible arms of the rotor towards the tower, and stop means on the rotor shaft to orient the blades in a vertical position during periods when the unit is upwind when the wind commences. A pendulum pitch control mechanism is improved by orienting the pivot axis for the pendulum arm at an angle to the longitudinal axis of its support arm, and excessive creep is of the synthetic resin flexible beam support for the blades is prevented by a restraining cable which limits the extent of pivoting of the pendulum during normal operation but which will permit further pivoting under abnormal conditions to cause the rotor to stall.

Wind energy is currently the fastest-growing renewable source of energy in India; India is a key market for the wind industry, presenting substantial opportunities for both the international and domestic players. In India the research is carried out on wind energy utilization on big ways.There are still many unsolved challenges in expanding wind power, and there are numerous problems of interest to systems and control researchers. In this paper we study the pitch control mechanism of windturbine. The pitch control system is one of the most widely used control techniques to regulate the output power of a windturbine generator. The pitch angle is controlled to keep the generator power at rated power by reducing the angle of the blades. By regulating, the angle of stalling, fast torque changes from the wind will be reutilized. It also describes the design of the pitch controller and discusses the response of the pitch-controlled system to wind velocity variations. The pitch control system is found to have a large output power variation and a large settling time.

Airfoils for the blade of a windturbine wherein each airfoil is characterized by a thickness in a range from 16%-24% and a maximum lift coefficient designed to be largely insensitive to roughness effects. The airfoils include a family of airfoils for a blade 15 to 25 meters in length, a family of airfoils for a blade 1 to 5 meters in length, and a family of airfoils for a blade 5 to 10 meters in length.

Airfoils are disclosed for the blade of a windturbine wherein each airfoil is characterized by a thickness in a range from 16%-24% and a maximum lift coefficient designed to be largely insensitive to roughness effects. The airfoils include a family of airfoils for a blade 15 to 25 meters in length, a family of airfoils for a blade 1 to 5 meters in length, and a family of airfoils for a blade 5 to 10 meters in length. 10 figs.

A turbinerotor blade with a spar and shell construction, and a tip cap that includes a row of lugs extending from a bottom side that form dovetail grooves that engage with similar shaped lugs and grooves on a tip end of the spar to secure the tip cap to the spar against radial displacement. The lug on the trailing edge end of the tip cap is aligned perpendicular to a chordwise line of the blade in the trailing edge region in order to minimize stress due to the lugs wanting to bend under high centrifugal loads. A two piece tip cap with lugs at different angles will reduce the bending stress even more.

Utility-scale windturbines operate in dynamic flows that can vary significantly over timescales from less than a second to several years. To better understand the inflow to utility-scale turbines, two inflow towers were installed and commissioned at the National Renewable Energy Laboratory's (NREL) National Wind Technology Center near Boulder, Colorado, in 2011. These towers are 135 m tall and instrumented with a combination of sonic anemometers, cup anemometers, wind vanes, and temperature measurements to characterize the inflow wind speed and direction, turbulence, stability and thermal stratification to two utility-scale turbines. Herein, we present variations in mean and turbulent wind parameters with height, atmospheric stability, and as a function of wind direction that could be important for turbine operation as well as persistence of turbine wakes. Wind speed, turbulence intensity, and dissipation are all factors that affect turbine performance. Our results shown that these all vary with height across the rotor disk, demonstrating the importance of measuring atmospheric conditions that influence windturbine performance at multiple heights in the rotor disk, rather than relying on extrapolation from lower levels.

Wind energy represents a viable alternative, as it is a virtually endless resource. Through the next several decades, renewable energy technologies, thanks to their continually improving performance and cost, and growing recognition of their Environmental, economic and social values, will grow increasingly competitive with Traditional energy technologies, so that by the middle of the 21 st century, renewable Energy, in its various forms, should be supplying half of the worlds energy needs. In this paper various types of windturbine are reviewed to understand and the development and modification of horizontal axis windturbine and how more power can be generated compared to bare turbine of the same rotor blade diameter.

A vertical axis wind machine called, ''Horizontal WindRotor'' conceived in 1979 by the Grantee E.J. Guard was an effort to marry a new high tech carousel type windrotor to a basic building design for the purpose of generating practical amounts of electricty. This was directed especially towards high performance power generation, relative to low average wind velocity fields, typically found in Florida. From January 1980 to April 1983 two 1/30 scale wind tunnel type test models of buildings, one round and one square were built. An eight Hartzell shrouded wind tunnel fan machine was designed and built to supply uniform wind velocities for testing. All components of the Horizontal WindRotor (HWR) were fabricated, instrumented, mounted on the building models, and tested and modified repeatedly for performance optimization. Aerodynamic consultants, model makers, mechanical and computer engineers and technicians under the direction of E. Guard all teamed up to evolve the size, shape, and placement of the system components. It was recognized early that the machine had to be large in order to extract energy from low wind velocities. It was also noted that there were so many variables in the system, so as to elude analytical computation, that only testing could provide the answers. Consequently, this grant program has provided major contributions to the sparse available data in this little studied field, and set up valuable bench marks in design and power output parameters. This data will be the foundation for incorporating the newly discovered design improvements into the full scale prototype to follow. (Phase II) It is believed that this Rotor design is the only one in the world today that will produce as much power in the lower wind velocity ranges and it is also believed that every objective of the original grant proposal has been met or exceeded.

An adaptor assembly for coupling a blade root of a turbine blade to a root slot of a rotor disk is described. The adaptor assembly includes a turbine blade having a blade root and an adaptor body having an adaptor root. The adaptor body defines a slot having an open end configured to receive the blade root of the turbine blade such that the adaptor root of the adaptor body and the blade root of the turbine blade are adjacent to one another when the blade root of the turbine blade is positioned within the slot. Both the adaptor root of the adaptor body and the blade root of the turbine blade are configured to be received within the root slot of the rotor disk.

Small windturbines often use some form of furling (yawing and/or tilting out of the wind) to protect against excessive power generation and rotor speeds in high winds.The verification study demonstrated the correct implementation of FAST's furling dynamics. During validation, the model tends to predict mean rotor speeds higher than measured in spite of the fact that the mean furl motion and rotor thrust are predicted quite accurately. This work has culminated with an enhanced version of FAST that should prove to be a valuable asset to designers of small windturbines.

Seminar and Workshop Installing Small WindTurbines Seminar and Workshop Location: Murdoch January 2011 Details for Registration and Payment: Mr Daniel Jones, National Small WindTurbine Test: The National Small WindTurbine Centre at Murdoch University is holding a Small WindTurbine short training

The primary goal of the Solar Energy Research Institute`s (SERI) advanced windturbine blades is to convert the kinetic energy in the wind into mechanical energy in an inexpensive and efficient manner. To accomplish this goal, advanced windturbine blades have been developed by SERI that utilize unique airfoil technology. Performance characteristics of the advanced blades were verified through atmospheric testing on fixed-pitch, stall-regulated horizontal-axis windturbines (HAWTs). Of the various windturbine configurations, the stall-regulated HAWT dominates the market because of its simplicity and low cost. Results of the atmospheric tests show that the SERI advanced blades produce 10% to 30% more energy than conventional blades. 6 refs.

The primary goal of the Solar Energy Research Institute's (SERI) advanced windturbine blades is to convert the kinetic energy in the wind into mechanical energy in an inexpensive and efficient manner. To accomplish this goal, advanced windturbine blades have been developed by SERI that utilize unique airfoil technology. Performance characteristics of the advanced blades were verified through atmospheric testing on fixed-pitch, stall-regulated horizontal-axis windturbines (HAWTs). Of the various windturbine configurations, the stall-regulated HAWT dominates the market because of its simplicity and low cost. Results of the atmospheric tests show that the SERI advanced blades produce 10% to 30% more energy than conventional blades. 6 refs.

This paper presents the current major modeling challenges for floating offshore windturbine design tools and describes aerodynamic and hydrodynamic effects due to rotor and platform motions and usage of non-slender support structures.

As the price of energy increases and windturbine technology matures, it is evident that cost effective designs for floating windturbines are needed. The next frontier for wind power is the ocean, yet development in near ...

In a turbine having closed-circuit steam-cooling passages about the rim of the rotor during steady-state operation, compressor discharge air is supplied to the rotor bore for passage radially outwardly into the wheel space cavities between the wheels and spacers. Communicating slots and channels in the spacers and wheels at circumferentially spaced positions enable egress of the compressor discharge air into the hot gas flow path. At turbine startup, cooling air flows through the closed-circuit steam passages to cool the outer rim of the rotor while compressor discharge air pre-warms the wheels and spacers. At steady-state, cooling steam is supplied in the closed-circuit steam-cooling passages and compressor discharge air is supplied through the bore and into the wheel space cavities to cool the rotor.

A variable-speed, constant-pitch windturbine was investigated to evaluate the feasibility of constraining its rotor speed and power output without the benefit of active aerodynamic control devices. A strategy was postulated to control rotational speed by specifying the demanded generator torque. By controlling rotor speed in relation to wind speed, the aerodynamic power extracted by the blades from the wind was manipulated. Specifically, the blades were caused to stall in high winds. In low and moderate winds, the demanded generator torque and the resulting rotor speed were controlled to cause the windturbine to operate near maximum efficiency. A computational model was developed, and simulations were conducted of operation in high turbulent winds. Results indicated that rotor speed and power output were well regulated. 7 refs., 7 figs.

Aerodynamic noise from windturbinerotors leads to constraints in both rotor design and turbine siting. The primary source of aerodynamic noise on windturbinerotors is the interaction of turbulent boundary layers on the blades with the blade trailing edges. This report surveys concepts that have been proposed for trailing edge noise reduction, with emphasis on concepts that have been tested at either sub-scale or full-scale. These concepts include trailing edge serrations, low-noise airfoil designs, trailing edge brushes, and porous trailing edges. The demonstrated noise reductions of these concepts are cited, along with their impacts on aerodynamic performance. An assessment is made of future research opportunities in trailing edge noise reduction for windturbinerotors.

Many small windturbine generators (10 kW or less) consist of a variable speed rotor driving a permanent magnet synchronous generator (alternator). One application of such windturbines is battery charging, in which the generator is connected through a rectifier to a battery bank. The windturbine electrical interface is essentially the same whether the turbine is part of a remote power supply for telecommunications, a standalone residential power system, or a hybrid village power system, in short, any system in which the wind generator output is rectified and fed into a DC bus. Field experience with such applications has shown that both the peak power output and the total energy capture of the windturbine often fall short of expectations based on rotor size and generator rating. In this paper, the authors present a simple analytical model of the typical wind generator battery charging system that allows one to calculate actual power curves if the generator and rotor properties are known. The model clearly illustrates how the load characteristics affect the generator output. In the second part of this paper, the authors present four approaches to maximizing energy capture from windturbines in battery charging applications. The first of these is to determine the optimal battery bank voltage for a given WTG. The second consists of adding capacitors in series with the generator. The third approach is to place an optimizing DC/DC voltage converter between the rectifier and the battery bank. The fourth is a combination of the series capacitors and the optimizing voltage controller. They also discuss both the limitations and the potential performance gain associated with each of the four configurations.

Airfoils for the tip and mid-span regions of a windturbine blade have upper surface and lower surface shapes and contours between a leading edge and a trailing edge that minimize roughness effects of the airfoil and provide maximum lift coefficients that are largely insensitive to roughness effects. The airfoil in one embodiment is shaped and contoured to have a thickness in a range of about fourteen to seventeen percent, a Reynolds number in a range of about 1,500,000 to 2,000,000, and a maximum lift coefficient in a range of about 1.4 to 1.5. In another embodiment, the airfoil is shaped and contoured to have a thickness in a range of about fourteen percent to sixteen percent, a Reynolds number in a range of about 1,500,000 to 3,000,000, and a maximum lift coefficient in a range of about 0.7 to 1.5. Another embodiment of the airfoil is shaped and contoured to have a Reynolds in a range of about 1,500,000 to 4,000,000, and a maximum lift coefficient in a range of about 1.0 to 1.5.

WindTurbines Electrical and Mechanical Engineering Objective · Introduce students to the concept of alternative energy. · Explain the math and scientific principles behind engineering windturbines. Standards and how it applies to wind energy · About how surface area and shape effects windturbine efficiency

windturbine flows. A few papers deal with applications of Blade Element Momentum (BEM) theory to wind, the BEM technique is employed by industry when designing new windturbine blades. However, in orderComputational Aerodynamics and Aeroacoustics for WindTurbines #12;#12;Computational Aerodynamics

A Fatigue Approach to WindTurbine Control Keld Hammerum Kongens Lyngby 2006 #12;Technical to the turbulent nature of wind, the structural components of a windturbine are exposed to highly varying loads. Therefore, fatigue damage is a major consideration when designing windturbines. The control scheme applied

See how windturbines generate clean electricity from the power of wind. The video highlights the basic principles at work in windturbines, and illustrates how the various components work to capture and convert wind energy to electricity. This updated version also includes information on the Energy Department's efforts to advance offshore wind power. Offshore wind energy footage courtesy of Vestas.

See how windturbines generate clean electricity from the power of wind. The video highlights the basic principles at work in windturbines, and illustrates how the various components work to capture and convert wind energy to electricity. This updated version also includes information on the Energy Department's efforts to advance offshore wind power. Offshore wind energy footage courtesy of Vestas.

This report provides an overview of the efforts aimed to establish a student focused laboratory apparatus that will enhance Purdue's ability to recruit and train students in topics related to the dynamics, operations and economics of windturbines. The project also aims to facilitate outreach to students at Purdue and in grades K-12 in the State of Indiana by sharing windturbine operational data. For this project, a portable windturbine test apparatus was developed and fabricated utilizing an AirX 400W wind energy converter. This turbine and test apparatus was outfitted with an array of sensors used to monitor wind speed, turbinerotor speed, power output and the tower structural dynamics. A major portion of this project included the development of a data logging program used to display real-time sensor data and the recording and creation of output files for data post-processing. The apparatus was tested in an open field to subject the turbine to typical operating conditions and the data acquisition system was adjusted to obtain desired functionality to facilitate use for student projects in existing courses offered at Purdue University and Indiana University. Data collected using the data logging program is analyzed and presented to demonstrate the usefulness of the test apparatus related to windturbine dynamics and operations.

The Sandia WindTurbine Loads Database is divided into six files, each corresponding to approximately 16 years of simulation. The files are text files with data in columnar format. The 424MB zipped file containing six data files can be downloaded by the public. The files simulate 10-minute maximum loads for the NREL 5MW windturbine. The details of the loads simulations can be found in the paper: Decades of WindTurbine Loads Simulations, M. Barone, J. Paquette, B. Resor, and L. Manuel, AIAA2012-1288 (3.69MB PDF). Note that the site-average wind speed is 10 m/s (class I-B), not the 8.5 m/s reported in the paper.

A vertical axis windturbine airfoil is described. The windturbine airfoil can include a leading edge, a trailing edge, an upper curved surface, a lower curved surface, and a centerline running between the upper surface and the lower surface and from the leading edge to the trailing edge. The airfoil can be configured so that the distance between the centerline and the upper surface is the same as the distance between the centerline and the lower surface at all points along the length of the airfoil. A plurality of such airfoils can be included in a vertical axis windturbine. These airfoils can be vertically disposed and can rotate about a vertical axis.

rotor bars and bearing damages. Index Terms--Windturbines, motor current signature analy- sis, time factors, such as wind speed and acoustic noise, wind parks are being mainly constructed offshore. Studies. Different methods of fault detection exist. These include monitoring of the acoustic vibration, internal

This article presents a collaborative research program that the Massachusetts Institute of Technology (MIT) and the National Renewable Energy Laboratory (NREL) have undertaken to develop innovative and cost-effective floating and mooring systems for offshore windturbines in water depths of 10-200 m. Methods for the coupled structural, hydrodynamic, and aerodynamic analysis of floating windturbine systems are presented in the frequency domain. This analysis was conducted by coupling the aerodynamics and structural dynamics code FAST [4] developed at NREL with the wave load and response simulation code WAMIT (Wave Analysis at MIT) [15] developed at MIT. Analysis tools were developed to consider coupled interactions between the windturbine and the floating system. These include the gyroscopic loads of the windturbinerotor on the tower and floater, the aerodynamic damping introduced by the windturbinerotor, the hydrodynamic damping introduced by wave-body interactions, and the hydrodynamic forces caused by wave excitation. Analyses were conducted for two floater concepts coupled with the NREL 5-MW Offshore Baseline windturbine in water depths of 10-200 m: the MIT/NREL Shallow Drafted Barge (SDB) and the MIT/NREL Tension Leg Platform (TLP). These concepts were chosen to represent two different methods of achieving stability to identify differences in performance and cost of the different stability methods. The static and dynamic analyses of these structures evaluate the systems' responses to wave excitation at a range of frequencies, the systems' natural frequencies, and the standard deviations of the systems' motions in each degree of freedom in various wind and wave environments. This article in various wind and wave environments. This article explores the effects of coupling the windturbine with the floating platform, the effects of water depth, and the effects of wind speed on the systems' performance. An economic feasibility analysis of the two concepts was also performed. Key cost components included the material and construction costs of the buoy; material and installation costs of the tethers, mooring lines, and anchor technologies; costs of transporting and installing the system at the chosen site; and the cost of mounting the windturbine to the platform. The two systems were evaluated based on their static and dynamic performance and the total system installed cost. Both systems demonstrated acceptable motions, and have estimated costs of $1.4-$1.8 million, not including the cost of the windturbine, the power electronics, or the electrical transmission.

STANDARDS FOR MEASUREMENTS AND TESTING OF WINDTURBINE POWER QUALITY Poul SÃ¸rensen, RisÃ¸ National and verification of windturbine power quality. The work has been organised in three major activities. The first farm summation on the power quality of windturbines with constant rotor speed. The third activity has

Designers of a horizontal axis windturbine yaw mechanism are faced with a difficult decision. They know that if they elect to use a yaw- controlled rotor then the system will suffer increased initial cost and increased inherent maintenance and reliability problems. On the other hand, if they elect to allow the rotor to freely yaw they known they will have to account for unknown and random, though bounded, yaw rates. They will have a higher-risk design to trade-off against the potential for cost savings and reliability improvement. The risk of a yaw-free system could be minimized if methods were available for analyzing and understanding yaw behavior. The complexity of yaw behavior has, until recently, discouraged engineers from developing a complete yaw analysis method. The objectives of this work are to (1) provide a fundamental understanding of free-yaw mechanics and the design concepts most effective at eliminating yaw problems, and (2) provide tested design tools and guidelines for use by free-yaw wind systems manufacturers. The emphasis is on developing practical and sufficiently accurate design methods.

Integrating Lidar to improve windturbine controls is a potential breakthrough for reducing the cost of wind energy. By providing undisturbed wind measurements up to 400m in front of the rotor, Lidar may provide an accurate update of the turbine inflow with a preview time of several seconds. Focusing on loads, several studies have evaluated potential reductions using integrated Lidar, either by simulation or full scale field testing.

A windturbine tower assembly for storing compressed gas such as hydrogen. The tower assembly includes a windturbine having a rotor, a generator driven by the rotor, and a nacelle housing the generator. The tower assembly includes a foundation and a tubular tower with one end mounted to the foundation and another end attached to the nacelle. The tower includes an in-tower storage configured for storing a pressurized gas and defined at least in part by inner surfaces of the tower wall. In one embodiment, the tower wall is steel and has a circular cross section. The in-tower storage may be defined by first and second end caps welded to the inner surface of the tower wall or by an end cap near the top of the tower and by a sealing element attached to the tower wall adjacent the foundation, with the sealing element abutting the foundation.

AbstractIn this paper, a data-driven methodology for the development of virtual models of a windturbine is presented. To demonstrate the proposed methodology, two parameters of the windturbine have been selected for modeling, namely, power output and rotor speed. A virtual model for each of the two parameters is developed and tested with data collected at a wind farm. Both models consider controllable and noncontrollable parameters of the windturbine, as well as the delay effect of wind speed and other parameters. To mitigate data bias of each virtual model and ensure its robustness, a training set is assembled from ten randomly selected turbines. The performance of a virtual model is largely determined by the input parameters selected and the data mining algorithms used to extract the model. Several data mining algorithms for parameter selection and model extraction are analyzed. The research presented in the paper is illustrated with computational results. Index TermsData mining, parameter selection, power prediction, virtual model, windturbine. I.

Floating Offshore WindTurbines (FOWT) is a technology that stands to spearhead the rapid growth of the offshore wind energy sector and allow the exploration of vast high quality wind resources over coastal and offshore ...

WindTurbine Blockset in Matlab/Simulink General Overview and Description of the Models Florin Iov, Anca Daniela Hansen, Poul SÃ¸rensen, Frede Blaabjerg Aalborg University March 2004 #12;22 WindTurbineturbine applications. This toolbox has been developed during the research project "Simulation Platform

A wind generator includes: a nacelle; a hub carried by the nacelle and including at least a pair of windturbine blades; and an electricity producing generator including a stator and a rotor carried by the nacelle. The rotor is connected to the hub and rotatable in response to wind acting on the blades to rotate the rotor relative to the stator to generate electricity. A cooling system is carried by the nacelle and includes at least one ambient air inlet port opening through a surface of the nacelle downstream of the hub and blades, and a duct for flowing air from the inlet port in a generally upstream direction toward the hub and in cooling relation to the stator.

Modern windturbines are fatigue critical machines that are typically used to produce electrical power from the wind. Operational experiences with these large rotating machines indicated that their components (primarily blades and blade joints) were failing at unexpectedly high rates, which led the windturbine community to develop fatigue analysis capabilities for windturbines. Our ability to analyze the fatigue behavior of windturbine components has matured to the point that the prediction of service lifetime is becoming an essential part of the design process. In this review paper, I summarize the technology and describe the ''best practices'' for the fatigue analysis of a windturbine component. The paper focuses on U.S. technology, but cites European references that provide important insights into the fatigue analysis of windturbines.

This report details the acoustic noise test conducted on the Gaia-Wind 11-kW windturbine at the National Wind Technology Center. The test turbine is a two- bladed, downwind windturbine with a rated power of 11 kW. The test turbine was tested in accordance with the International Electrotechnical Commission standard, IEC 61400-11 Ed 2.1 2006-11 WindTurbine Generator Systems -- Part 11 Acoustic Noise Measurement Techniques.

Terrace irrigation along the rivers of Nepal is the vital problem of farmers in the remote villages. The existing turbines and irrigation systems are not feasible without civil structures, and suffer from the lack of resources and financial problems. A simple and inexpensive underwater Free Rotor River Turbine (FRRT) which extracts power ranging from a fraction of a HP up to 25 HP from the velocity of the running water in a river or stream was developed. The power obtained from the turbine can be used to run a pump to lift water for drinking purposes and for irrigation along the river banks during the dry season and early part of the wet season. Various designs of models have been tested in the laboratory to find the optimum pitch angle, shape and size of blades, and optimum number of blades in order to accomplish the cheapest, simplest, and most efficient turbine. The effect of diameter of turbine, velocity of water and torque produced by the turbines were studied,and the effect of simple linear twist on blades is discussed.

To develop a practical inline inspection that could be used in combination with automated composite material placement equipment to economically manufacture high performance and reliable carbon composite windturbine blade spar caps. The approach technical feasibility and cost benefit will be assessed to provide a solid basis for further development and implementation in the windturbine industry. The program is focused on the following technology development: (1) Develop in-line monitoring methods, using optical metrology and ultrasound inspection, and perform a demonstration in the lab. This includes development of the approach and performing appropriate demonstration in the lab; (2) Develop methods to predict composite strength reduction due to defects; and (3) Develop process models to predict defects from leading indicators found in the uncured composites.

Orbital Research Inc is developing an innovative Plasma Aerodynamic Control Effectors (PACE) technology for improved performance of windturbines. The PACE system is aimed towards the design of "smart" rotor blades to enhance energy capture and reduce aerodynamic loading and noise using flow-control. The PACE system will provide ability to change aerodynamic loads and pitch distribution across the windturbine blade without any moving surfaces. Additional benefits of the PACE system include reduced blade structure weight and complexity that should translate into a substantially reduced initial cost. During the Phase I program, the ORI-UND Team demonstrated (proof-of-concept) performance improvements on select rotor blade designs using PACE concepts. Control of both 2-D and 3-D flows were demonstrated. An analytical study was conducted to estimate control requirements for the PACE system to maintain control during wind gusts. Finally, independent laboratory experiments were conducted to identify promising dielectric materials for the plasma actuator, and to examine environmental effects (water and dust) on the plasma actuator operation. The proposed PACE system will be capable of capturing additional energy, and reducing aerodynamic loading and noise on windturbines. Supplementary benefits from the PACE system include reduced blade structure weight and complexity that translates into reduced initial capital costs.

The Small Wind Research Turbine (SWRT) project was initiated to provide reliable test data for model validation of furling windturbines and to help understand small windturbine loads. This report will familiarize the user with the scope of the SWRT test and support the use of these data. In addition to describing all the testing details and results, the report presents an analysis of the test data and compares the SWRT test data to simulation results from the FAST aeroelastic simulation model.

This report summarizes the results of a safety and function test that NREL conducted on the Ventera VT10 windturbine. This test was conducted in accordance with the International Electrotechnical Commissions' (IEC) standard, WindTurbine Generator System Part 2: Design requirements for small windturbines, IEC 61400-2 Ed.2.0, 2006-03.

This report summarizes the results of a safety and function test that NREL conducted on the Entegrity EW50 windturbine. This test was conducted in accordance with the International Electrotechnical Commissions' (IEC) standard, WindTurbine Generator System Part 2: Design requirements for small windturbines, IEC 61400-2 Ed.2.0, 2006-03.

An advanced aileron configuration for windturbinerotors featuring an independent, lift generating aileron connected to the rotor blade. The aileron has an airfoil profile which is inverted relative to the airfoil profile of the main section of the rotor blade. The inverted airfoil profile of the aileron allows the aileron to be used for strong positive control of the rotation of the rotor while deflected to angles within a control range of angles. The aileron functions as a separate, lift generating body when deflected to angles within a shutdown range of angles, generating lift with a component acting in the direction opposite the direction of rotation of the rotor. Thus, the aileron can be used to shut down rotation of the rotor. The profile of the aileron further allows the center of rotation to be located within the envelope of the aileron, at or near the centers of pressure and mass of the aileron. The location of the center of rotation optimizes aerodynamically and gyroscopically induced hinge moments and provides a fail safe configuration.

Washington University Can the Sound Generated by Modern WindTurbines Affect the Health of Those turbines haveWindturbines have been getting biggerbeen getting bigger and bigger....and bigger.... Lars Needs Windturbines are "green" and areWindturbines are "green" and are contributing to our energy

In a gas turbine, a bore tube assembly radially inwardly of an aft bearing conveys cooling steam to the buckets of the turbine and returns the cooling steam to a return. To cool the bearing and thermally insulate the bearing from the cooling steam paths, a radiation shield is spaced from the bore tube assembly by a dead air gap. Additionally, an air passageway is provided between the radiation shield and the inner surface of an aft shaft forming part of the rotor. Air is supplied from an inlet for flow along the passage and radially outwardly through bores in the aft shaft disk to cool the bearing and insulate it from transfer of heat from the cooling steam.

Wind Energy is becoming a significant source of energy throughout the world. This ever increasing field will potentially reach the limit of availability and practicality with the wind farm sites and size of the turbine itself. Therefore...

Under U.S. Department of Energy-sponsored research FOA 415, the National Renewable Energy Laboratory led a team of research groups to produce a complete design of a large windturbine system to be deployable in the western Gulf of Mexico region. As such, the turbine and its support structure would be subjected to hurricane-loading conditions. Among the goals of this research was the exploration of advanced and innovative configurations that would help decrease the levelized cost of energy (LCOE) of the design, and the expansion of the basic IEC design load cases (DLCs) to include hurricane environmental conditions. The windturbine chosen was a three-bladed, downwind, direct-drive, 10-MW rated machine. The rotor blade was optimized based on an IEC load suite analysis. The drivetrain and nacelle components were scaled up from a smaller sized turbine using industry best practices. The tubular steel tower was sized using ultimate load values derived from the rotor optimization analysis. The substructure is an innovative battered and raked jacket structure. The innovative turbine has also been modeled within an aero-servo-hydro-elastic tool, and future papers will discuss results of the dynamic response analysis for select DLCs. Although multiple design iterations could not be performed because of limited resources in this study, and are left to future research, the obtained data will offer a good indication of the expected LCOE for large offshore windturbines to be deployed in subtropical U.S. waters, and the impact design innovations can have on this value.

A preliminary system-level, computational model was developed to allow broad assessment and optimization of windturbine design and costs analysis at The Wind Energy Research Center, Solar Energy Research Institute under contract to the US Department of Energy (DOE). This paper briefly describes the basic principles used in the model for energy capture and cost-of-energy (COE), and demonstrates the model's usefulness in determining the effects of rotor and system design modifications. The model's utilization for conducting parametric studies and defining the energy cost of small and medium-sized windturbines is also shown. Topics of interest to windturbine engineers and designers include the effects on rotor performance of airfoil geometry, blade pitch angle setting, and the system RPM schedule, etc.

The use of wind power has recently emerged as a promising alternative to conventional electricity generation. However, space requirements and public pressure to place unsightly windturbines out of visual range make it ...

#12;#12;1Design limits and solutions for very large windturbines UpWind Design limits and solutions for very large windturbines A 20 MW turbine is feasible March 2011 Supported by: #12;March 20112 Photo:Nordex #12;3Design limits and solutions for very large windturbines Contents 1. UpWind: Summary

Simulation models of a variable-speed, fixed-pitch windturbine were investigated to evaluate the feasibility of constraining rotor speed and power output without the benefit of active aerodynamic control devices. A strategy was postulated to control rotational speed by specifying the demanded generator torque. By controlling rotor speed in relation to wind speed, the aerodynamic power extracted by the blades from the wind was manipulated. Specifically, the blades were caused to stall in high winds. In low and moderate winds, the demanded generator torque and the resulting rotor speed were controlled to cause the windturbine to operate near maximum efficiency. Using the developed models, simulations were conducted of operation in turbulent winds. Results indicated that rotor speed and power output were well regulated. Preliminary investigations of system dynamics showed that, compared to fixed-speed operation, variable-speed operation caused cyclic loading amplitude to be reduced for the turbine blades and low-speed shaft and slightly increased for the tower loads. This result suggests a favorable impact on fatigue life from implementation of the proposed control strategy.

The objective of this project is to develop the capability of symbolically generating an analytical model of a windturbine for studies of control systems. This report focuses on a theoretical formulation of the symbolic equations of motion (EOMs) modeler for horizontal axis windturbines. In addition to the power train dynamics, a generic 7-axis rotor assembly is used as the base model from which the EOMs of various turbine configurations can be derived. A systematic approach to generate the EOMs is presented using d`Alembert`s principle and Lagrangian dynamics. A Matlab M file was implemented to generate the EOMs of a two-bladed, free yaw windturbine. The EOMs will be compared in the future to those of a similar windturbine modeled with the YawDyn code for verification. This project was sponsored by Sandia National Laboratories as part of the Adaptive Structures and Control Task. This is the final report of Sandia Contract AS-0985.

Aerodynamic, load, flow-visualization, and inflow measurements were taken on a downwind horizontal-axis windturbine (HAWT). A video camera mounted on the rotor recorded video images of tufts attached to the low-pressure side of the blade. Strain gages, mounted every 10% of the blade's span, provided load and pressure measurements. Pressure taps at 32 chordwise positions recorded pressure distributions. Wind inflow was measured via a vertical-plane array of anemometers located 10 m upwind. The objectives of the test were to address whether airfoil pressure distributions measured on a rotating blade differed from those measured in the wind tunnel, if radial flow near or in the boundary layer of the airfoil affected pressure distributions, if dynamic stall could result in increased dynamic loads, and if the location of the separation boundary measured on the rotating blade agreed with that measured in two-dimensional flow in the wind tunnel. 6 refs., 9 figs., 1 tab.

This report, which focuses on the meteorological aspects of siting large windturbines (turbines with a rated output exceeding 100 kW), has four main goals. The first is to outline the elements of a siting strategy that will identify the most favorable wind energy sites in a region and that will provide sufficient wind data to make responsible economic evaluations of the site wind resource possible. The second is to critique and summarize siting techniques that were studied in the Department of Energy (DOE) Wind Energy Program. The third goal is to educate utility technical personnel, engineering consultants, and meteorological consultants (who may have not yet undertaken wind energy consulting) on meteorological phenomena relevant to windturbine siting in order to enhance dialogues between these groups. The fourth goal is to minimize the chances of failure of early siting programs due to insufficient understanding of wind behavior.

ABSTRACT Structural responses and power output of a windturbine are strongly affected by the wind field acting on the windturbine. Knowledge about the wind field and its variations is essential not only for designing, but also for cost-efficiently managing windturbines. Wind field monitoring

In a turbinerotor, an aft shaft wheel and the final-stage wheel of the rotor are coupled together, including by a rabbeted joint. During shutdown and startup of the turbine, a thermal mismatch between the aft shaft wheel and final-stage wheel is avoided by respectively heating and cooling the aft shaft wheel to maintain the thermal mismatch within acceptable limits, thereby avoiding opening of the rabbeted joint and the potential for unbalancing the rotor and rotor vibration. The thermal medium may be supplied by piping in the aft bearing cavity into the cavity between the forward closure plate and the aft shaft wheel.

A semi-empirical method is applied to calculate the time-average sound level of windturbine noise generation and propagation. Both are affected by wind shear refraction. Under upwind conditions the partially ensonified zone separates the fully ensonified zone (close to the turbine) and the shadow zone (far away from the turbine). Refraction is described in terms of the wind speed linear profile fitted to the power law profile. The rotating blades are treated as a two-dimensional circular source in the vertical plane. Inside the partially ensonified zone the effective A-weighted sound power decreases to zero when the receiver moves from the turbine toward the shadow zone. The presented results would be useful in practical applications to give a quick estimate of the effect of refraction on windturbine noise.

Aeroelastic simulation tools are routinely used to design and analyze onshore windturbines, in order to obtain cost effective machines that achieve favorable performance while maintaining structural integrity. These tools employ sophisticated models of wind-inflow; aerodynamic, gravitational, and inertial loading of the rotor, nacelle, and tower; elastic effects within and between components; and mechanical actuation and electrical responses of the generator and of control and protection systems. For offshore windturbines, additional models of the hydrodynamic loading in regular and irregular seas, the dynamic coupling between the support platform motions and windturbine motions, and the dynamic characterization of mooring systems for compliant floating platforms are also important. Hydrodynamic loading includes contributions from hydrostatics, wave radiation, and wave scattering, including free surface memory effects. The integration of all of these models into comprehensive simulation tools, capable of modeling the fully coupled aeroelastic and hydrodynamic responses of floating offshore windturbines, is presented.

The use of induction generators in wind power applications has been common since the early development of the wind industry. Most of these generators operate at fixed frequency and are connected directly to the utility grid. Unfortunately, this mode of operation limits the rotor speed to a specific rpm. Variable-speed operation is preferred in order to facilitate maximum energy capture over a wide range of wind speeds. This paper explores variable-speed operating strategies for windturbine applications. The objectives are to maximize energy production, provide controlled start-up and reduce torque loading. This paper focuses on optimizing the energy captured by operating at maximum aerodynamic efficiency at any wind speed. The control strategy we analyze uses rotor speed and generator power as the feedback signals. In the normal operating region, rotor speed is used to compute a target power that corresponds to optimum operation. With power as the control objective, the power converter and generator are controlled to track the target power at any rpm. Thus, the torque-speed characteristic of the generator is shaped to optimize the energy capture. The target power is continuously updated at any rpm. in extreme areas of the operating envelope, during start-up, shutdown, generator overload, or overspeed, different strategies driven by other system considerations must be used.

The use of induction generators in wind power applications has been common since the early development of the wind industry. Most of these generators operate at fixed frequency and are connected directly to the utility grid. Unfortunately, this mode of operation limits the rotor speed to a specific rpm. Variable-speed operation is preferred in order to facilitate maximum energy capture over a wide range of wind speeds. This paper explores variable-speed operating strategies for windturbine applications. The objectives are to maximize energy production, provide controlled start-up and reduce torque loading. This paper focuses on optimizing the energy captured by operating at maximum aerodynamic efficiency at any wind speed. The control strategy analyzed uses rotor speed and generator power as the feedback signals. In the normal operating region, rotor speed is used to compute a target power that corresponds to optimum operation. With power as the control objective, the power converter and generator are controlled to track the target power at any rpm. Thus, the torque-speed characteristic of the generator is shaped to optimize the energy capture. The target power is continuously updated at any rpm. In extreme areas of the operating envelope, during start-up, shutdown, generator overload, or overspeed, different strategies driven by other system considerations must be used.

The use of induction generators in wind power applications has been common since the early development of the wind industry. Most of these generators operate at fixed frequency and are connected directly to the utility grid. Unfortunately, this mode of operation limits the rotor speed to a specific rpm. Variable speed operation is preferred in order to facilitate maximum energy capture over a wide range of wind speeds. This paper explores variable speed operating strategies for windturbine applications. The objectives are to maximize energy production, provide controlled start-up, and reduce torque loading. This paper focuses on optimizing the energy captured by operating at maximum aerodynamic efficiency at any wind speed. The control strategy the authors analyze uses rotor speed and generator power as the feedback signals. In the normal operating region, rotor speed is used to compute a target power that corresponds to optimum operation. With power as the control objective, the power converter and generator are controlled to track the target power at any rpm. Thus, the torque-speed characteristic of the generator is shaped to optimize the energy capture. The target power is continuously updated at any rpm. In extreme areas of the operating envelope, during start-up, shutdown, generator overload, or overspeed, different strategies driven by other system considerations must be used.

Doctoral Position Aeroelastic Analysis of Large WindTurbines In the research project "Aeroelastic Analysis Horizontal-axis windturbine and numerical model. of Large WindTurbines" funded by the Ger- man involving the in-house Finite-Element CFD code XNS to enable the simulation of windturbines. The ability

call both liquids and gases "fluids" Â­ i.e. things that flow). A windturbine's blades use aerodynamic of a typical windturbine are: - Rotor: a windturbine's blades and the hub to which they attach form the rotor or planning wind power. It focuses on commercial and medium-scale windturbine technology available

An adaptor assembly for coupling a blade root of a turbine blade to a root slot of a rotor disk is disclosed. The adaptor assembly may generally include an adaptor body having a root configured to be received within the root slot. The adaptor body may also define a slot having an open end configured to receive the blade root. The adaptor body may further define a channel. The adaptor assembly may also include a plate having an outwardly extending foot. The foot may be configured to be received within the channel. Additionally, the plate may be configured to cover at least a portion of the open end of the slot when the foot is received within the channel.

As part of the U.S. Department-of-Energy-funded Competitiveness Improvement Project, the National Renewable Energy Laboratory (NREL) developed new capabilities for aeroelastic modeling of precurved and preswept blades for small windturbines. This presentation covers the quest for optimized rotors, computer-aided engineering tools, a case study, and summary of the results.

Portable remote sensing devices are increasingly needed to cost effectively characterize the meteorology at a potential wind energy site as the size of modern windturbines increase. A short term project co-locating a Sound Detection and Ranging System (SODAR) with a 200 meter instrumented meteorological tower at the Texas Tech Wind Technology Field Site was performed to collect and summarize wind information through an atmospheric layer typical of utility scale rotor plane depths. Data collected identified large speed shears and directional shears that may lead to unbalanced loads on the rotors. This report identifies suggestions for incorporation of additional data in wind resource assessments and a few thoughts on the potential for using a SODAR or SODAR data to quantify or investigate other parameters that may be significant to the wind industry.

Due to its renewable nature and abundant resources, wind energy has the potential to fulfill a large portion of this nation`s energy needs. The simplest means of utilizing wind energy is through the use of downwind, horizontal-axis windturbines (HAWT) with fixed-pitch rotors. This configuration regulates the peak power by allowing the rotor blade to aerodynamically stall. The stall point, the point of maximum coefficient of lift, is currently predicted using data obtained from wind tunnel tests. Unfortunately, these tests do not accurately simulate conditions encountered in the field. Flow around the tower and nacelle coupled with inflow turbulence and rotation of the turbine blades create unpredicted aerodynamic forces. Dynamic stall is hypothesized to occur. Such aerodynamic loads are transmitted into the rotor and tower causing structural resonance that drastically reduces the design lifetime of the windturbine. The current method of alleviating this problem is to structurally reinforce the tower and blades. However, this adds unneeded mass and, therefore, cost to the turbines. A better understanding of the aerodynamic forces and the manner in which they affect the structure would allow for the design of more cost effective and durable windturbines. Data compiled by the National Renewable Energy Laboratory (NREL) for a downwind HAWT with constant chord, untwisted, fixed-pitch rotors is analyzed. From these data, the actual aerodynamic characteristics of the rotor are being portrayed and the potential effects upon the structure can for the first time be fully analyzed. Based upon their understanding, solutions to the problem of structural resonance are emerging.

This report describes the design of a centrifugally actuated aerodynamic-overspeed device for a horizontal-axis windturbine. The device will meet the following criteria; (1) It will be effective for airfoil angles of attack 0{degrees} to 45{degrees}. (2) It will be stowed inside the blade profile prior to deployment. (3) It will be capable of offsetting the positive torque produced by the overall blade. (4) Hinge moments will be minimized to lower actuator loads and cost. (5) It will be evaluated as a potential power modulating active rotor-control system. A literature review of aerodynamic braking devices was conducted. Information from the literature review was used to conceptualize the most effective devices for subsequent testing and design. Wind-tunnel test data for several braking devices are presented in this report. Using the data for the most promising configuration, a preliminary design was developed for a MICON 65/13 windturbine with Phoenix 7.9-m rotor blades.

PROJECT OBJECTIVE The PowerJet windturbine overcomes problems characteristic of the small windturbines that are on the market today by providing reliable output at a wide range of wind speeds, durability, silent operation at all wind speeds, and bird-safe operation. Prime EnergyÃ¢Â?Â?s objective for this project was to design and integrate a generator with an electrical controller and mechanical controls to maximize the generation of electricity by its windturbine. The scope of this project was to design, construct and test a mechanical back plate to control rotational speed in high winds, and an electronic controller to maximize power output and to assist the base plate in controlling rotational speed in high winds. The test model will continue to operate beyond the time frame of the project, with the ultimate goal of manufacturing and marketing the PowerJet worldwide. Increased Understanding of Electronic & Mechanical Controls Integrated With Electricity Generator The PowerJet back plate begins to open as wind speed exceeds 13.5 mps. The pressure inside the turbine and the turbine rotational speed are held constant. Once the back plate has fully opened at approximately 29 mps, the controller begins pulsing back to the generator to limit the rotational speed of the turbine. At a wind speed in excess of 29 mps, the controller shorts the generator and brings the turbine to a complete stop. As the wind speed subsides, the controller releases the turbine and it resumes producing electricity. Data collection and instrumentation problems prevented identification of the exact speeds at which these events occur. However, the turbine, controller and generator survived winds in excess of 36 mps, confirming that the two over-speed controls accomplished their purpose. Technical Effectiveness & Economic Feasibility Maximum Electrical Output The output of electricity is maximized by the integration of an electronic controller and mechanical over-speed controls designed and tested during the course of this project. The output exceeds that of the PowerJetÃ¢Â?Â?s 3-bladed counterparts (see Appendix). Durability All components of the PowerJet turbine assemblyÃ¢Â?Â?including the electronic and mechanical controls designed, manufactured and field tested during the course of this projectÃ¢Â?Â?proved to be durable through severe weather conditions, with constant operation and no interruption in energy production. Low Cost Materials for the turbine, generator, tower, charge controllers and ancillary parts are available at reasonable prices. Fabrication of these parts is also readily available worldwide. The cost of assembling and installing the turbine is reduced because it has fewer parts and requires less labor to manufacture and assemble, making it competitively priced compared with turbines of similar output manufactured in the U.S. and Europe. The electronic controller is the unique part to be included in the turbine package. The controllers can be manufactured in reasonably-sized production runs to keep the cost below $250 each. The data logger and 24 sensors are for research only and will be unnecessary for the commercial product. Benefit To Public The PowerJet wind-electric system is designed for distributed wind generation in 3 and 4 class winds. This windturbine meets DOEÃ¢Â?Â?s requirements for a quiet, durable, bird-safe turbine that eventually can be deployed as a grid-connected generator in urban and suburban settings. Results As described more fully below and illustrated in the Appendices, the goals and objectives outlined in 2060 SOPO were fully met. Electronic and mechanical controls were successfully designed, manufactured and integrated with the generator. The turbine, tower, controllers and generators operated without incident throughout the test period, surviving severe winter and summer weather conditions such as extreme temperatures, ice and sustained high winds. The electronic controls were contained in weather-proof electrical boxes and the elec

One of the primary advantages of variable-speed windturbines over fixed-speed turbines should be improved aerodynamic efficiency. With variable-speed generation, in order to maintain a constant ratio of wind speed to tip speed, the windturbine changes rotor speed as the wind speed changes. In this paper we compare a stall-controlled, variable-speed windturbine to a fixed-speed turbine. The focus of this paper is to investigate the effects of variable speed on energy capture and its ability to control peak power. We also show the impact of turbulence on energy capture in moderate winds. In this report, we use a dynamic simulator to apply different winds to a windturbine model. This model incorporates typical inertial and aerodynamic performance characteristics. From this study we found a control strategy that makes it possible to operate a stall-controlled turbine using variable speed to optimize energy capture and to control peak power. We also found that turbulence does not have a significant impact on energy capture.

Induction generator has been used since the early development of utility-scale windturbine generation. An induction generator is the generator of choice because of its ruggedness and low cost. With an induction generator, the operating speed of the windturbine is limited to a narrow range (almost constant speed). Dual- speed operation can be accomplished by using an induction generator with two different sets of winding configurations or by using a dual output drive train to drive two induction generators with two different rated speeds. With single-speed operation, the windturbine operates at different power coefficients (Cp) as the wind speed varies. Operation at maximum Cp can occur only at a single wind speed. However, if the wind speed.varies across a wider range, the operating Cp will vary significantly. Dual-speed operation has the advantage of enabling the windturbine to operate at near maximum Cp over a wider range of wind speeds. Thus, annual energy production can be increased. The dual-speed mode may generate less energy than a variable-speed mode; nevertheless, it offers an alternative which captures more energy than single-speed operation. In this paper, dual-speed operation of a windturbine is investigated. Annual energy production is compared between single-speed and dual-speed operation. One type of control algorithm for dual-speed operation is proposed. Some results from a dynamic simulation will be presented to show how the control algorithm works as the windturbine is exposed to varying wind speeds.

This paper provides an overview of windturbine drivetrain condition monitoring based on presentations from a condition monitoring workshop organized by the National Renewable Energy Laboratory in 2009 and on additional references.

A diffuser for augmenting a windturbine having means for energizing the boundary layer at several locations along the diffuser walls is improved by the addition of a short collar extending radially outward from the outlet of the diffuser.

This work presents Tower Flex, a structural dynamics model for a coupled analysis of offshore floating windturbines consisting of a tower, a floating platform and a mooring system. In this multi-body, linear frequency-domain ...

This test was conducted as part of the U.S. Department of Energy's (DOE) Independent Testing project. This project was established to help reduce the barriers to wind energy expansion by providing independent testing results for small windturbines (SWT). In total, five turbines were tested at the National Wind Technology Center (NWTC) as a part of this project. Safety and function testing is one of up to five tests performed on the turbines, including power performance, duration, noise, and power-quality tests. NWTC testing results provide manufacturers with reports that may be used to meet part of small windturbine certification requirements. The test equipment includes a Mariah Windspire windturbine mounted on a monopole tower. L&E Machine manufactured the turbine in the United States. The inverter was manufactured separately by Technology Driven Products in the United States. The system was installed by the NWTC site operations group with guidance and assistance from Mariah Power.

A windturbine is provided that passively cools an electrical generator. The windturbine includes a plurality of fins arranged peripherally around a generator house. Each of the fins being oriented at an angle greater than zero degrees to allow parallel flow of air over the fin. The fin is further tapered to allow a constant portion of the fin to extend beyond the air stream boundary layer. Turbulence initiators on the nose cone further enhance heat transfer at the fins.

Large-eddy simulations of atmospheric boundary layers under various stability and surface roughness conditions are performed to investigate the turbulence impact on windturbines. In particular, the aeroelastic responses of the turbines are studied to characterize the fatigue loading of the turbulence present in the boundary layer and in the wake of the turbines. Two utility-scale 5 MW turbines that are separated by seven rotor diameters are placed in a 3 km by 3 km by 1 km domain. They are subjected to atmospheric turbulent boundary layer flow and data is collected on the structural response of the turbine components. The surface roughness was found to increase the fatigue loads while the atmospheric instability had a small influence. Furthermore, the downstream turbines yielded higher fatigue loads indicating that the turbulent wakes generated from the upstream turbines have significant impact.

Variable-speed, horizontal axis windturbines use blade-pitch control to meet specified objectives for three operational regions. This paper provides a guide for controller design for the constant power production regime. A simple, rigid, non-linear turbine model was used to systematically perform trade-off studies between two performance metrics. Minimization of both the deviation of the rotor speed from the desired speed and the motion of the actuator is desired. The robust nature of the proportional-integral-derivative controller is illustrated, and optimal operating conditions are determined. Because numerous simulation runs may be completed in a short time, the relationship between the two opposing metrics is easily visualized.

The usage of industrial steam turbines in different industrial branches (chemistry, petrochemistry, refineries, sugar and ethanol plants, etc.) for a generator drive for electricity generation or a mechanical drive for compressors, blowers and pumps, is characterized by the need for high flexibility of operation. High flexibility includes numerous start-ups, shut-downs and power changes during the useful life. Changes in power and steam mass flow lead to changes of the working fluid state in the single turbine stages, and thus their aerodynamic and thermodynamic characteristics. During these transient working regimes in steam turbinerotors, large space and time-dependent temperature gradients appear, which can result in high non-stationary temperature stresses, i.e. increased local stress concentrations, what has a negative impact on the useful life of the rotor. In the worst case they can cause fracture of the turbinerotor. Today, for the determination of thermal stressed state of the steam turbine parts the user softwares based on numerical methods are used. In this paper the results of numerical modelling and calculations of non-stationary temperature fields and related stresses in the rotor of industrial steam turbine of 35 MW power during transient operating regime (a cold startup) will be presented. The results of the calculations serve for estimation of the transient regime impact on the stresses of the rotor, as well as on its entire useful life. Key words: industrial steam turbine, transient regimes, temperature stresses, numerical modelling 1.

An air jet spoiler arrangement is provided for a Darrieus-type vertical axis wind-powered turbine. Air is drawn into hollow turbine blades through air inlets at the ends thereof and is ejected in the form of air jets through small holes or openings provided along the lengths of the blades. The air jets create flow separation at the surfaces of the turbine blades, thereby inducing stall conditions and reducing the output power. A feedback control unit senses the power output of the turbine and controls the amount of air drawn into the air inlets accordingly.

An air jet spoiler arrangement is provided for a Darrieus-type vertical axis wind-powered turbine. Air is drawn into hollow turbine blades through air inlets at the end thereof and is ejected in the form of air jets through small holes or openings provided along the lengths of the blades. The air jets create flow separation at the surfaces of the turbine blades, thereby including stall conditions and reducing the output power. A feedback control unit senses the power output of the turbine and controls the amount of air drawn into the air inlets accordingly.

Early expensive in automatic operation of the Sandia 17-m vertical axis research windturbine (VAWT) has demonstrated the need for a systematic study of control algorithms. To this end, a computer model has been developed that uses actual wind time series and turbine performance data to calculate the power produced by the Sandia 17-m VAWT operating in automatic control. The model has been used to investigate the influence of starting algorithms on annual energy production. The results indicate that, depending on turbine and local wind characteristics, a bad choice of a control algorithm can significantly reduce overall energy production. The model can be used to select control algorithms and threshold parameters that maximize long-term energy production. An attempt has been made to generalize these results from local site and turbine characteristics to obtain general guidelines for control algorithm design.

Wind energy is a viable option to complement other types of pollution-free generation. In the early development of wind energy, the majority of windturbines were operated at constant speed. Recently, the number of variable-speed windturbines installed in wind farms has increased and more windturbine manufacturers are making variable-speed windturbines. This paper covers the operation of variable-speed windturbines with pitch control. The system the authors considered is controlled to generate maximum energy while minimizing loads. The maximization of energy was only carried out on a static basis and only drive train loads were considered as a constraint. In medium wind speeds, the generator and power converter control the windturbine to capture maximum energy from the wind. In the high wind speed region, the windturbine is controlled to maintain the aerodynamic power produced by the windturbine. Two methods to adjust the aerodynamic power were investigated: pitch control and generator load control, both of which are employed to control the operation of the windturbine. The analysis and simulation shows that the windturbine can be operated at its optimum energy capture while minimizing the load on the windturbine for a wide range of wind speeds.

Physically measuring the dynamic responses of windturbine support structures enables the calculation of the applied loads using an inverse procedure. In this process, inverse means deriving the inputs/forces from the outputs/responses. This paper presents results of a numerical verification of such an inverse load calculation. For this verification, the comprehensive simulation code FAST is used. FAST accounts for the coupled dynamics of wind inflow, aerodynamics, elasticity and turbine controls. Simulations are run using a 5-MW onshore windturbine model with a tubular tower. Both the applied loads due to the instantaneous wind field and the resulting system responses are known from the simulations. Using the system responses as inputs to the inverse calculation, the applied loads are calculated, which in this case are the rotor thrust forces. These forces are compared to the rotor thrust forces known from the FAST simulations. The results of these comparisons are presented to assess the accuracy of the inverse calculation. To study the influences of turbine controls, load cases in normal operation between cut-in and rated wind speed, near rated wind speed and between rated and cut-out wind speed are chosen. The presented study shows that the inverse load calculation is capable of computing very good estimates of the rotor thrust. The accuracy of the inverse calculation does not depend on the control activity of the windturbine.

TECHNICALADVANCES IN EPOXY TECHNOLOGY FOR WINDTURBINE BLADE COMPOSITE FABRICATION George C. Jacob reliability in many demanding applications including components for aerospace and windturbine blades. While in operation, windturbine blades are subjected to significant stresses from their movement, wind and other

Dynamic Simulation of DFIG WindTurbines on FPGA Boards Hao Chen, Student Member, IEEE, Song Sun is a friction coefficient. The windturbine model is based on the relation between the upstream wind speed V w + 1 where p is the air density; Rw is the windturbine radius; cp (A, (3) is the performance

RisÃ¸-R-1111(EN) Ultimate Loading of WindTurbines Gunner Chr. Larsen, Knut Ronold, Hans E analysis as well as a windturbine reliability study. In the wind climate analysis, the distribution to analyse windturbine components with respect to failure in ultimate loading, and in addition to establish

Quantifying the hurricane risk to offshore windturbines Stephen Rosea , Paulina Jaramilloa,1. Turbine tower buckling has been observed in typhoons, but no offshore windturbines have yet been built be destroyed by hurricanes in an offshore wind farm. We apply this model to estimate the risk to offshore wind

Three models for making automated forecasts of subhourly wind and wind power fluctuations were examined to determine the models' appropriateness, accuracy, and reliability in wind forecasting for windturbine operation. Such automated forecasts appear to have value not only in windturbine control and operating strategies, but also in improving individual windturbine control and operating strategies, but also in improving individual windturbine operating strategies (such as determining when to attempt startup). A simple persistence model, an autoregressive model, and a generalized equivalent Markhov (GEM) model were developed and tested using spring season data from the WKY television tower located near Oklahoma City, Oklahoma. The three models represent a pure measurement approach, a pure statistical method and a statistical-dynamical model, respectively. Forecasting models of wind speed means and measures of deviations about the mean were developed and tested for all three forecasting techniques for the 45-meter level and for the 10-, 30- and 60-minute time intervals. The results of this exploratory study indicate that a persistence-based approach, using onsite measurements, will probably be superior in the 10-minute time frame. The GEM model appears to have the most potential in 30-minute and longer time frames, particularly when forecasting wind speed fluctuations. However, several improvements to the GEM model are suggested. In comparison to the other models, the autoregressive model performed poorly at all time frames; but, it is recommended that this model be upgraded to an autoregressive moving average (ARMA or ARIMA) model. The primary constraint in adapting the forecasting models to the production of windturbine cluster power output forecasts is the lack of either actual data, or suitable models, for simulating windturbine cluster performance.

Micropitting is a Hertzian fatigue phenomenon that affects many windturbine gearboxes, and it affects the reliability of the machines. With the major growth and increasing dependency on renewable energy, mechanical reliability is an extremely important issue. The U.S. Department of Energy has made a commitment to improving windturbine reliability and the National Renewable Energy Laboratory (NREL) has started a gearbox reliability project. Micropitting as an issue that needed attention came to light through this effort. To understand the background of work that had already been accomplished, and to consolidate some level of collective understanding of the issue by acknowledged experts, NREL hosted a windturbine micropitting workshop, which was held at the National Wind Technology Center in Boulder, Colorado, on April 15 and 16, 2009.

The U.S. Energy Department's Sandia National Laboratories will host its 2014 Sandia WindTurbine Blade Workshop at the Marriott Pyramid North in Albuquerque, New Mexico. The workshop provides a unique, blade focused collaborative forum that will bring together wind energy leaders from industry, academia, and government. Stay tuned for updates. Information regarding past Wind Workshops can be found at: http://windworkshops.sandia.gov/.

A method for reducing peak loads of windturbines in a changing wind environment includes measuring or estimating an instantaneous wind speed and direction at the windturbine and determining a yaw error of the windturbine relative to the measured instantaneous wind direction. The method further includes comparing the yaw error to a yaw error trigger that has different values at different wind speeds and shutting down the windturbine when the yaw error exceeds the yaw error trigger corresponding to the measured or estimated instantaneous wind speed.

. Design details of the windturbine are discussed by the sections shown in the figure . Main Su ort Assembl The 3/4 in. diameter rotor shaft is supported at each end by roller bearings. Each bearing is clamped between two aluminum blocks. A flange...THE EXPERIMENTAL AND THEORETICAL INVESTIGATION OF A HORIZONTAL-AXIS WINDTURBINE A Thesis by ROBERT TERRANCE MILBURN Submitted to the Graduate College of Texas A&M University in partial fulfillment of the requirement for the degree of MASTER...

This test was conducted as part of the U.S. Department of Energy's (DOE) Independent Testing project to help reduce the barriers of wind energy expansion by providing independent testing results for small turbines. In total, five turbines are being tested at the National Wind Technology Center (NWTC) as a part of the first round of this project. Duration testing is one of up to five tests that may be performed on the turbines. Other tests include power performance, safety and function, noise, and power quality tests. NWTC testing results provide manufacturers with reports that may be used to meet part of small windturbine certification requirements. This duration test report focuses on the Mariah Power Windspire windturbine.

This is a study of the impact that windturbines have on residential property value. The windturbines that are the focus of this study are the larger turbines being approximately 389ft tall and producing 1.0+ megawatts each, similar to the one pictured to the right. The study has been broken into three component parts, each looking at the value impact of the windturbines from a different perspective. The three parts are: (1) a literature study, which reviews and summarizes what has been published on this matter found in the general media; (2) an opinion survey, which was given to area Realtors to learn their opinions on the impact of windturbines in

Conventional three dimensional structural analysis methods prove to be expensive for the preliminary design of windturbine blades. However, windturbine blades are large slender members with complex cross sections. They can be accurately modeled...

A probabilistic framework is developed to assess the structural reliability of offshore windturbines. Probabilistic models are developed to predict the deformation, shear force and bending moment demands on the support structure of windturbines...

Optimum extraction of energy from a windturbine requires that turbine speed vary with wind speed. Existing solutions to produce constant-frequency electrical output under windspeed variations are undesirable due to ...

A probabilistic framework is developed to assess the structural reliability of offshore windturbines. Probabilistic models are developed to predict the deformation, shear force and bending moment demands on the support structure of windturbines...

structures of the type encountered in windturbine blades, helicopter rotor blades, and the like such as windturbine blades lead to a splitting of the problem into a (usually) linear, two-dimensional cross

An advanced aileron configuration for windturbinerotors featuring an aileron with a bottom surface that slopes upwardly at an angle toward the nose region of the aileron. The aileron rotates about a center of rotation which is located within the envelope of the aileron, but does not protrude substantially into the air flowing past the aileron while the aileron is deflected to angles within a control range of angles. This allows for strong positive control of the rotation of the rotor. When the aileron is rotated to angles within a shutdown range of deflection angles, lift-destroying, turbulence-producing cross-flow of air through a flow gap, and turbulence created by the aileron, create sufficient drag to stop rotation of the rotor assembly. The profile of the aileron further allows the center of rotation to be located within the envelope of the aileron, at or near the centers of pressure and mass of the aileron. The location of the center of rotation optimizes aerodynamically and gyroscopically induced hinge moments and provides a fail safe configuration.

The paper presents a stochastic approach to estimate the aerodynamic forces with local dynamics on windturbine blades in unsteady wind inflow. This is done by integrating a stochastic model of lift and drag dynamics for an airfoil into the aerodynamic simulation software AeroDyn. The model is added as an alternative to the static table lookup approach in blade element momentum (BEM) wake model used by AeroDyn. The stochastic forces are obtained for a rotor blade element using full field turbulence simulated wind data input and compared with the classical BEM and dynamic stall models for identical conditions. The comparison shows that the stochastic model generates additional extended dynamic response in terms of local force fluctuations. Further, the comparison of statistics between the classical BEM, dynamic stall and stochastic models' results in terms of their increment probability density functions gives consistent results.

The Effect of Wind Speed and Electric Rates On WindTurbine Economics Economics of wind power depends mainly on the wind speeds and the turbine make and model. Definition: Simple Payback The "Simple period of a small wind power project. All the figures are per turbine, so it can be used for a one, two

Dynamic loads must be predicted accurately in order to estimate the fatigue life of windturbines operating in turbulent environments. Dynamic stall contributes to increased dynamic loads during normal operation of all types of horizontal-axis windturbine (HAWTs). This report illustrates how dynamic stall varies throughout the blade span of a 10 m HAWT during yawed and unyawed operating conditions. Lift, drag, and pitching moment coefficients during dynamics stall are discussed. Resulting dynamic loads are presented, and the effects of dynamic stall on yaw loads are demonstrated using a yaw loads dynamic analysis (YAWDYN). 12 refs., 22 figs., 1 tab.

A Simplified Morphing Blade for Horizontal Axis WindTurbines Weijun WANG , St´ephane CARO, Fouad salinas@hotmail.com The aim of designing windturbine blades is to improve the power capture ability by adjusting the twist of the blade's root and tip. To evaluate the performance of windturbine blades

AIAAÂ­98Â­0057 RELATING TURBULENCE TO WINDTURBINE BLADE LOADS: PARAMETRIC STUDY WITH MULTIPLE that is most useful in estimating fatigue loads on windturbine blades. The histograms of rainflow counted turbulence measures---can be used to estimate fatigue loads on windturbine blades. We first deÂ­ scribe

Sparkær Blade Test Centre Modal Analysis of WindTurbine Blades Modal analysis is the process the modes constitute a complete dynamic description of the windturbine blade. The modes of vibration represent the inherent dynamic properties of the windturbine blade. The range of applications for modal

, the windturbine blades can experience large changes in angle of attack associated with sudden large gusts, horizontal axis windturbines. These blade/inflow/tower wake interactions can result in dynamic stall overAIAA-2004-1184 1 AN AEROACOUSTIC ANALYSIS OF WINDTURBINES* Philip J. Morris, Lyle N. Long

Modelling of transient windturbine loads during pitch motion Niels.N. Sørensen, Helge Aa. Madsen In connection with the design of windturbines and their control algorithms, the transient loads, especially widespread tool in the windturbine industry, the time constants necessary to describe these problems

Vortex Lattice Modelling of Winglets on WindTurbine Blades Mads DÃ¸ssing RisÃ¸-R-1621(EN) RisÃ¸ Title: Vortex Lattice Modelling of Winglets on WindTurbine Blades Departments: Wind Energy Department turbines can be increased by the use of winglets without increasing the swept area. This makes them

SOUND COMPLIANCE MONITORING FOR THE GAMESA WINDTURBINE UD - LEWES, DELAWARE January 2011 ` #12;SOUND COMPLIANCE MONITORING FOR THE GAMESA WINDTURBINE AT THE UNIVERSITY OF DELAWARE LEWES, DELAWARE A Gamesa G90 2.0-MW windturbine operates at the University of Delaware (UD), Lewes campus on a parcel

Disturbance Control of the Hydraulic Brake in a WindTurbine Frank Jepsen, Anders SÃ¸borg brake in a windturbine. Brake torque is determined by friction coefficient and clamp force; the latter brake is one1 of the two independent brake systems in a windturbine. As a consequence of the gearing

Mechanisms of amplitude modulation in windturbine noise M. Smitha , A. J. Bullmoreb , M. M. Candb produced by windturbines is inherently time varying. This amplitude modulation is normally due The environmental noise impact of windturbine generators has to be assessed when planning new installations

LIGHTNING EXPOSURE OF WINDTURBINES Dale Dolan University of Toronto e-mail: dale@ecf.utoronto.ca Abstract This paper applies the electrogeometric model of lightning exposure to a windturbine to compute. For a typical 45 m windturbine, the probability of being struck by a downward negative flash, as predicted

This report summarizes the results of a duration test that NREL conducted on the Entegrity EW50 windturbine. This test was conducted in accordance with the International Electrotechnical Commissions' (IEC) standard, WindTurbine Generator System Part 2: Design requirements for small windturbines, IEC 61400-2 Ed.2.0, 2006-03.

Fast Verification of WindTurbine Power Curves: Summary of Project Results by: Cameron Brown Â­ s equation on high frequency windturbine measurement data sampled at one sample per second or more. The aim's Nordtank windturbine at the RisÃ¸ site, the practical application of this new method was tested

204 1 Development of WindTurbines Prototyping Software Under Matlab/SimulinkÂ® Through present the development of a windturbine prototyping software under Matlab/SimulinkÂ® through and the end of 1999, around 75% of all new grid-connected windturbines worldwide were installed in Europe [3

Control of WindTurbines for Power Regulation and Load Reduction Juan Jose Garcia Quirante Kongens regulation and load reduction and their ensemble in a variable-speed windturbine. The power regulation aspects of mathematical modelling of windturbines, and especially the control methods suited for power

Low frequency noise from MW windturbines -- mechanisms of generation and its modeling Helge MW windturbines -- mechanisms of generation and its modeling Department: Department of Wind Energy turbine has been simulated with a noise prediction model from NASA in US. Running the model

Climatological wind shear analyses relevant to the design and operation of multimegawatt windturbines are provided. Insight is provided for relating the wind experienced by a rotating blade in a shear flow to the analysis results. A simple analysis of the wind experienced by a rotating blade for three types of wind shear profiles under steady-state conditions is presented in graphical form. Comparisons of the magnitude and frequency of the variations in 1) the wind sensed by a single blade element, 2) the sum, and 3) the difference of the winds sensed by opposite blade elements show strong sensitivity to profile shape. These three items represent forcing functions that can be related to 1) flatwise bending moment, 2) torque on the shaft, and 3) teeter angle. A computer model was constructed to simulate rotational sampling of 10-s sampled winds from a tall tower for three different types of large windturbines. Time series produced by the model indicated that the forcing functions on a rotating blade vary according to the shear profile encountered during each revolution as opposed to a profile derived from average wind conditions, e.g., hourly average winds. An analysis scheme was developed to establish a climatology of wind shear profiles derived from 10-s sampled winds and hourly average winds measured over a one-year period at several levels on a tall tower. Because of the sensitivity of the forcing function variability to profile shape, the analyses performed and presented are in the form of joint frequency distributions of velocity differences of the the top-to-hub versus the hub-to-bottom portion of disks of rotation for the three turbine configurations.

1 WINDTURBINE SITING IN AN URBAN ENVIRONMENT: THE HULL, MA 660 KW TURBINE J. F. Manwell, J. G. Mc turbine at Windmill Point in Hull, Massachusetts represents a high point in the long history of wind, through the installation of a 40 kW Enertech machine in the 1980's to the installation of the new turbine

When an induction generator is connected to a utility bus, the voltage and frequency at the terminal of the generator are the same as the voltage and frequency of the utility. The reactive power needed by the induction generator is supplied by the utility and the real power is returned to the utility. The rotor speed varies within a very limited range, and the reactive power requirement must be transported through a long line feeder, thus creating additional transmission losses. The energy captured by a windturbine can be increased if the rotor speed can be adjusted to follow wind speed variations. For small applications such as battery charging or water pumping, a stand alone operation can be implemented without the need to maintain the output frequency output of the generator. A self- excited induction generator is a good candidate for a stand alone operation where the windturbine is operated at variable speed. Thus the performance of the windturbine can be unproved. In this paper, we examine a self-excited induction generator operated in a stand alone mode. A potential application for battery charging is given. The output power of the generator will be controlled to improve the performance of the windturbine.

This paper reviews issues related to the use of aeroelastic tailoring as a cost-effective, passive means to shape the power curve and reduce loads. Windturbine blades bend and twist during operation, effectively altering the angle of attack, which in turn affects loads and energy production. There are blades now in use that have significant aeroelastic couplings, either on purpose or because of flexible and light-weight designs. Since aeroelastic effects are almost unavoidable in flexible blade designs, it may be desirable to tailor these effects to the authors advantage. Efforts have been directed at adding flexible devices to a blade, or blade tip, to passively regulate power (or speed) in high winds. It is also possible to build a small amount of desirable twisting into the load response of a blade with proper asymmetric fiber lay up in the blade skin. (Such coupling is akin to distributed {delta}{sub 3} without mechanical hinges.) The tailored twisting can create an aeroelastic effect that has payoff in either better power production or in vibration alleviation, or both. Several research efforts have addressed different parts of this issue. Research and development in the use of aeroelastic tailoring on helicopter rotors is reviewed. Potential energy gains as a function of twist coupling are reviewed. The effects of such coupling on rotor stability have been studied and are presented here. The ability to design in twist coupling with either stretching or bending loads is examined also.

Although only a small contributor to total electricity production needs, built-environment windturbines (BWTs) nonetheless have the potential to influence the public's consideration of renewable energy, and wind energy in particular. Higher population concentrations in urban environments offer greater opportunities for project visibility and an opportunity to acquaint large numbers of people to the advantages of wind projects on a larger scale. However, turbine failures will be equally visible and could have a negative effect on public perception of wind technology. This roadmap provides a framework for achieving the vision set forth by the attendees of the Built-Environment WindTurbine Workshop on August 11 - 12, 2010, at the U.S. Department of Energy's National Renewable Energy Laboratory. The BWT roadmap outlines the stakeholder actions that could be taken to overcome the barriers identified. The actions are categorized as near-term (0 - 3 years), medium-term (4 - 7 years), and both near- and medium-term (requiring immediate to medium-term effort). To accomplish these actions, a strategic approach was developed that identifies two focus areas: understanding the built-environment wind resource and developing testing and design standards. The authors summarize the expertise and resources required in these areas.

Windturbine system reliability is a critical factor in the success of a wind energy project. Poor reliability directly affects both the project's revenue stream through increased operation and maintenance (O&M) costs and reduced availability to generate power due to turbine downtime. Indirectly, the acceptance of wind-generated power by the financial and developer communities as a viable enterprise is influenced by the risk associated with the capital equipment reliability; increased risk, or at least the perception of increased risk, is generally accompanied by increased financing fees or interest rates. This paper outlines the issues relevant to windturbine reliability for windturbine power generation projects. The first sections describe the current state of the industry, identify the cost elements associated with wind farm O&M and availability and discuss the causes of uncertainty in estimating windturbine component reliability. The latter sections discuss the means for reducing O&M costs and propose O&M related research and development efforts that could be pursued by the wind energy research community to reduce cost of energy.

This report summarizes the results of a power performance test that NREL conducted on the SWIFT windturbine. This test was conducted in accordance with the International Electrotechnical Commission's (IEC) standard, WindTurbine Generator Systems Part 12: Power Performance Measurements of Electricity Producing WindTurbines, IEC 61400-12-1 Ed.1.0, 2005-12. However, because the SWIFT is a small turbine as defined by IEC, NREL also followed Annex H that applies to small windturbines. In these summary results, wind speed is normalized to sea-level air density.

Tribology is the science and engineering of interacting surfaces in relative motion. It includes the study and application of the principles of friction, lubrication, and wear. It is an important phenomenon that not only impacts the design and operation of windturbine gearboxes, but also their subsequent maintenance requirements and overall reliability. With the major growth and increasing dependency on renewable energy, mechanical reliability is an extremely important issue. The WindTurbine Tribology Seminar was convened to explore the state-of-the-art in windturbine tribology and lubricant technologies, raise industry awareness of a very complex topic, present the science behind each technology, and identify possible R&D areas. To understand the background of work that had already been accomplished, and to consolidate some level of collective understanding of tribology by acknowledged experts, the National Renewable Energy Laboratory (NREL), Argonne National Laboratory (ANL), and the U.S. Department of Energy (DOE) hosted a windturbine tribology seminar. It was held at the Renaissance Boulder Flatiron Hotel in Broomfield, Colorado on November 15-17, 2011. This report is a summary of the content and conclusions. The presentations given at the meeting can be downloaded. Interested readers who were not at the meeting may wish to consult the detailed publications listed in the bibliography section, obtain the cited articles in the public domain, or contact the authors directly.

A thick airfoil for the root region of the blade of a windturbine. The airfoil has a thickness in a range from 24%-26% and a Reynolds number in a range from 1,000,000 to 1,800,000. The airfoil has a maximum lift coefficient of 1.4-1.6 that has minimum sensitivity to roughness effects.

A wooden windturbine blade is formed by laminating wood veneer in a compression mold having the exact curvature needed for one side of the blade, following which the other side of the blade is ground flat along its length but twisted with respect to the blade axis.

The current designs of windturbine hubs contain many faults. The slew ring bearing that connects the blade to the hub takes on a large bending moment that in many cases causes the joints to fail and the blade to break ...

A major goal of the federal Wind Energy Program is the rapid development and validation of structural models to determine loads and response for a wide variety of different windturbine configurations operating under extreme conditions. Such codes are crucial to the successful design of future advanced windturbines. In previous papers the authors described steps they took to develop a model of a two-bladed teetering-hub downwind windturbine using ADAMS{reg_sign} (Automatic Dynamic Analysis of Mechanical Systems), as well as comparison of model predictions to test data. In this paper they show the use of this analytical model to study the influence of various turbine parameters on predicted system loads. They concentrate their study on turbine response in the frequency range of six to ten times the rotor rotational frequency (6P to 10P). Their goal is to identify the most important parameters which influence the response of this type of machine in this frequency range and give turbine designers some general design guidelines for designing two-bladed teetering-hub machines to be less susceptible to vibration. They study the effects of such parameters as blade edgewise and flapwise stiffness, tower top stiffness, blade tip-brake mass, low-speed shaft stiffness, nacelle mass momenta of inertia, and rotor speed. They show which parameters can be varied in order to make the turbine less responsive to such atmospheric inputs as wind shear and tower shadow. They then give designers a set of design guidelines in order to show how these machines can be designed to be less responsive to these inputs.

Sandia National Laboratories (SNL) and Verdant Power Inc. (VPI) have partnered under a Cooperative Research and Development Agreement (CRADA) to develop a new kinetic hydropower rotor. The rotor features an improved hydrodynamic and structural design which features state-of-the-art technology developed for the wind industry. The new rotor will have higher energy capture, increased system reliability, and reduction of overall cost of energy. This project was divided into six tasks: (1) Composite Rotor Project Planning and Design Specification; (2) Baseline Fatigue Testing and Failure analysis; (3) Develop Blade/Rotor Performance Model; (4) Hydrofoil Survey and Selection; (5) FEM Structural Design; and (6) Develop Candidate Rotor Designs and Prepare Final Report.

This report summarizes the results of a duration noise test that the National Renewable Energy Laboratory (NREL) conducted on the Viryd CS8 windturbine. This test was conducted in accordance with Clause 9.4 of the International Electrotechnical Commission's (IEC) standard, Windturbines - Part 2: Design requirements for small windturbines, IEC 61400-2 Ed. 2.0:2006-03. NREL researchers evaluated the turbine based on structural integrity and material degradation, quality of environmental protection, and dynamic behavior.

Multi-megawatt, utility-scale windturbines operate in turbulent and dynamic winds that impact turbine performance in ways that are gradually becoming better understood. This poster presents a study made using a turbulent flow field simulator (TurbSim) and a Turbine aeroelastic simulator (FAST) of the response of a generic 1.5 MW windturbine to changing inflow. The turbine power output is found to be most sensitive to wind speed and turbulence intensity, but the relationship depends on the wind speed with respect to the turbine's rated wind speed. Shear is found to be poorly correlated to power. A machine learning method called 'regression trees' is used to create a simple model of turbine performance that could be used as part of the wind resource assessment process. This study has used simple flow fields and should be extended to more complex flows, and validated with field observations.

Response of a Vertical Axis WindTurbine to Time Varying Wind Conditions found within the Urban, 2010 PP 389Â­401 389 ABSTRACT Experimental testing of a vertical axis windturbine within the urban of the turbine. Temporal variation of the wind with respect to the direction and velocity fluctuations

1 WIND-TUNNEL STUDY ON AERODYNAMIC PERFORMANCE OF SMALL VERTICAL-AXIS WINDTURBINES J. J. Miau*1 were carried out to study the aerodynamic performance of three vertical axis windturbines (VAWTs. On the other hand, the characteristics of unsteady flow around the helical windturbine were studied with a hot

This test was conducted on the ARE 442 as part of the U.S. Department of Energy's (DOE's) Independent Testing project. This project was established to help reduce the barriers of wind energy expansion by providing independent testing results for small turbines. In total, five turbines are being tested at the National Wind Technology Center (NWTC) as a part of this project. Acoustic noise testing is one of up to five tests that may be performed on the turbines, including duration, safety and function, power performance, and power quality tests. The acoustic noise test was conducted to the IEC 61400-11 Edition 2.1.

In support of DOE's efforts to further develop distributed wind technology, NREL's National Wind Technology Center has released a Request for Proposal for the following Distributed WindTurbine Competitiveness Improvement Projects on the Federal Business

The primary objective of this report was to develop universal manufacturer-independent windturbine and wind power plant models that can be shared, used, and improved without any restrictions by project developers, manufacturers, and engineers. Manufacturer-specific models of windturbines are favored for use in wind power interconnection studies. While they are detailed and accurate, their usages are limited to the terms of the non-disclosure agreement, thus stifling model sharing. The primary objective of the work proposed is to develop universal manufacturer-independent wind power plant models that can be shared, used, and improved without any restrictions by project developers, manufacturers, and engineers. Each of these models includes representations of general turbine aerodynamics, the mechanical drive-train, and the electrical characteristics of the generator and converter, as well as the control systems typically used. To determine how realistic model performance is, the performance of one of the models (doubly-fed induction generator model) has been validated using real-world wind power plant data. This work also documents selected applications of these models.

Ris R1024EN Design of the WindTurbine Airfoil Family RIS AXX Kristian S. Dahl, Peter Fuglsang Ris National Laboratory, Roskilde, Denmark December 1998 #12;Abstract A method for design of windturbineturbine. The airfoils are designed to have maximum lift-drag ratio until just below stall, a design lift

Deep C Wind, a consortium headed by the University of Maine will test the first U.S. offshore wind platforms in 2012. In advance of final siting and permitting of the test turbines off Monhegan Island, residents of the island off Maine require reassurance that the noise levels from the test turbines will not disturb them. Pacific Northwest National Laboratory, at the request of the University of Maine, and with the support of the U.S. Department of Energy Wind Program, modeled the acoustic output of the planned test turbines.

The objective of this study was to provide a fatigue load comparison between two identical windturbines employing different rotor designs. One turbine was fitted with a rotor consisting of a set of NREL (SERI) thin-airfoil blades while the other rotor included the original-equipment AeroStar blades. The data discussed are based on sample load populations derived from the rainflow cycle counting of 405, 10-minute records specifically collected over a wide range of inflow turbulence conditions. The results have shown that the statistical structure of the alternating load cycles on both turbines can be described as a mixture of three stochastic processes. We noted a high degree of load distribution similarity between the two turbines, with the differences attributable to either rotor weight or swept area.

The objective of the study described in this report is to examine the nature of wind shear profiles and their variability over the height of large horizontal-axis windturbines and to provide information on wind shear relevant to the design and opertion of large windturbines. Windturbine fatigue life and power quality are related through the forcing functions on the blade to the shapes of the wind shear profiles and their fluctuations over the disk of rotation.

change, there is a strong urge to move away from fossil fuel driven economies to a more sustainable energy supply with renewable power at its core. The UK has embodied its ambition for more green power generation in a series of legally binding obligations... in the UK over the last 12 years [Renewable UK, 2012b]. The UK has the best wind resource of any country in Europe [Renewable UK, 2012a, p.3] and, with the support of government subsidies, has seen rapid growth in the amount of installed wind generating...

36 SEPTEMBER | 2012 WiNdTURbiNE CAPACiTY FRONTiER FROM SCAdA ThE WORld hAS SEEN A significant contributor to this growth. The windturbine generated energy depends on the wind potential and the turbine of windturbines. Supervi- sory control and data acquisition (SCADA) systems record windturbine

This test was conducted as part of the U.S. Department of Energy's (DOE) Independent Testing project. This project was established to help reduce the barriers of wind energy expansion by providing independent testing results for small turbines. In total, five turbines are being tested at the National Renewable Energy Laboratory's (NRELs) National Wind Technology Center (NWTC) as a part of this project. Duration testing is one of up to five tests that may be performed on the turbines, including power performance, safety and function, noise, and power quality tests. The results of the testing will provide the manufacturers with reports that may be used for small windturbine certification. The test equipment includes a Gaia-Wind 11 kW windturbine mounted on an 18 m monopole tower. Gaia-Wind Ltd. manufactured the turbine in Denmark, although the company is based in Scotland. The system was installed by the NWTC Site Operations group with guidance and assistance from Gaia-Wind.

This report documents the status of the Sandia National Laboratories' Wind Plant Reliability Database. Included in this report are updates on the form and contents of the Database, which stems from a fivestep process of data partnerships, data definition and transfer, data formatting and normalization, analysis, and reporting. Selected observations are also reported.

The objective of this effort was to investigate and characterize the nature of surface damage and wear to windturbine gearbox bearings returned from service in the field. Bearings were supplied for examination by S. Butterfield and J. Johnson of the National Wind Technology Center (NREL), Boulder, Colorado. Studies consisted of visual examination, optical and electron microscopy, dimensional measurements of wear-induced macro-scale and micro-scale features, measurements of macro- and micro-scale hardness, 3D imaging of surface damage, studies of elemental distributions on fracture surfaces, and examinations of polished cross-sections of surfaces under various etched and non-etched conditions.

Nontorque loads induced by the windturbinerotor overhang weight and aerodynamic forces can greatly affect drivetrain loads and responses. If not addressed properly, these loads can result in a decrease in gearbox component life. This work uses analytical modeling, computational modeling, and experimental data to evaluate a unique drivetrain design that minimize the effects of nontorque loads on gearbox reliability: the Pure Torque drivetrain developed by Alstom. The drivetrain has a hub-support configuration that transmits nontorque loads directly into the tower rather than through the gearbox as in other design approaches. An analytical model of Alstom's Pure Torque drivetrain provides insight into the relationships among turbine component weights, aerodynamic forces, and the resulting drivetrain loads. Main shaft bending loads are orders of magnitude lower than the rated torque and are hardly affected by wind speed and turbine operations.

A thick airfoil is described for the root region of the blade of a windturbine. The airfoil has a thickness in a range from 24%--26% and a Reynolds number in a range from 1,000,000 to 1,800,000. The airfoil has a maximum lift coefficient of 1.4--1.6 that has minimum sensitivity to roughness effects. 3 Figs.

The development of technologically advanced, higher efficiency windturbines has been identified as a high priority activity by the US wind industry. The Department of Energy`s Wind Energy Program has begun a multi-year development program aimed at assisting the wind industry with the design, development, and testing of advanced windturbine systems that can compete with conventional electric generation for $0.05/kWh at 13 mph sites by the mid-1990s and with fossil-fuel-based generators for $0.04/kWh at 13 mph sites by the year 2000. The development plan consists of four phases: (1) Conceptual Design Studies; (2) Near-Term Product Development; (3) Next Generation Technology Integration and Design, and (4) Next- Generation Technology Development and Testing. The Conceptual Design Studies were begun in late 1990, and are scheduled for completion in the Spring of 1992. Preliminary results from these analyses are very promising and indicate that the goals stated above are technically feasible. This paper includes a brief summary of the Conceptual Design Studies and presents initial plans for the follow-on activities. 3 refs., 4 figs.

The development of technologically advanced, higher efficiency windturbines has been identified as a high priority activity by the US wind industry. The Department of Energy's Wind Energy Program has begun a multi-year development program aimed at assisting the wind industry with the design, development, and testing of advanced windturbine systems that can compete with conventional electric generation for $0.05/kWh at 13 mph sites by the mid-1990s and with fossil-fuel-based generators for $0.04/kWh at 13 mph sites by the year 2000. The development plan consists of four phases: (1) Conceptual Design Studies; (2) Near-Term Product Development; (3) Next Generation Technology Integration and Design, and (4) Next- Generation Technology Development and Testing. The Conceptual Design Studies were begun in late 1990, and are scheduled for completion in the Spring of 1992. Preliminary results from these analyses are very promising and indicate that the goals stated above are technically feasible. This paper includes a brief summary of the Conceptual Design Studies and presents initial plans for the follow-on activities. 3 refs., 4 figs.

Utility-oriented guidelines are described for identifying viable sites for windturbines. Topics and procedures are also discussed that are important in carrying out a windturbine siting program. These topics include: a description of the Department of Energy wind resource atlases; procedures for predicting windturbine performance at potential sites; methods for analyzing windturbine economics; procedures for estimating installation and maintenance costs; methods for anlayzing the distribution of wind resources over an area; and instrumentation for documenting wind behavior at potential sites. The procedure described is applicable to small and large utilities. Although the procedure was developed as a site-selection tool, it can also be used by a utility who wishes to estimate the potential for windturbine penetration into its future generation mix.

innovati nNREL Computer Models Integrate WindTurbines with Floating Platforms Far off the shores of energy-hungry coastal cities, powerful winds blow over the open ocean, where the water is too deep for today's seabed-mounted offshore windturbines. For the United States to tap into these vast offshore

Wave Models for Offshore WindTurbines Puneet Agarwal§ and Lance Manuely Department of Civil. These wave modeling assumptions do not adequately represent waves in shallow waters where most offshore wind for estimating loads on the support structure (monopile) of an offshore windturbine. We use a 5MW utility

Extreme Loads for an Offshore WindTurbine using Statistical Extrapolation from Limited Field Data,itiscommontoeithercarry out extensive simulation studies or undertake a field measurement campaign. At the Blyth offshore wind here is to estimate extreme loads for an offshore windturbine for which the environmental and load

of the evidence from current literature on the issue of windturbines and potential impacts on human health: There are no direct pathological effects from wind farms and that any potential impact on humans can be minimised regarding windturbines and their potential effect on human health. It is important to note that these views

The accurate prediction of windturbine blade loads and response is important in predicting the fatigue life of wind machines. At the SERI Wind Energy Research Center, a rotor code called FLAP (Force and Loads Analysis Program) is currently being validated by comparing predicted results to machine measurements. The FLAP code has been modified to allow the teetering degrees of freedom. This paper describes these modifications and comparisons of predicted blade bending moments to test measurements. Wind tunnel data for a 1/20th scale model will be used to compare FLAP predictions for the cyclic flap-bending moments at the 33% spanwise station for three different wind speeds. The comparisons will be made for both rigid and teetering hubs. Currently, the FLAP code accounts for deterministic excitations such as wind shear, tower shadow, gravity, and prescribed yawing motions. Conclusions will be made regarding the code's accuracy in predicting the cyclic bending moments.

In recent years, increasing deployment of large wind-turbine farms has become an issue of growing concern for the radar community. The large radar cross section (RCS) presented by windturbines interferes with radar operation, and the Doppler shift caused by blade rotation causes problems identifying and tracking moving targets. Each new wind-turbine farm installation must be carefully evaluated for potential disruption of radar operation for air defense, air traffic control, weather sensing, and other applications. Several approaches currently exist to minimize conflict between wind-turbine farms and radar installations, including procedural adjustments, radar upgrades, and proper choice of low-impact wind-farm sites, but each has problems with limited effectiveness or prohibitive cost. An alternative approach, heretofore not technically feasible, is to reduce the RCS of windturbines to the extent that they can be installed near existing radar installations. This report summarizes efforts to reduce wind-turbine RCS, with a particular emphasis on the blades. The report begins with a survey of the wind-turbine RCS-reduction literature to establish a baseline for comparison. The following topics are then addressed: electromagnetic model development and validation, novel material development, integration into wind-turbine fabrication processes, integrated-absorber design, and wind-turbine RCS modeling. Related topics of interest, including alternative mitigation techniques (procedural, at-the-radar, etc.), an introduction to RCS and electromagnetic scattering, and RCS-reduction modeling techniques, can be found in a previous report.

A conceptual design has been completed for a 10MW superconducting direct drive windturbine generator employing low temperature superconductors for the field winding. Key technology building blocks from the GE Wind and GE Healthcare businesses have been transferred across to the design of this concept machine. Wherever possible, conventional technology and production techniques have been used in order to support the case for commercialization of such a machine. Appendices A and B provide further details of the layout of the machine and the complete specification table for the concept design. Phase 1 of the program has allowed us to understand the trade-offs between the various sub-systems of such a generator and its integration with a windturbine. A Failure Modes and Effects Analysis (FMEA) and a Technology Readiness Level (TRL) analysis have been completed resulting in the identification of high risk components within the design. The design has been analyzed from a commercial and economic point of view and Cost of Energy (COE) calculations have been carried out with the potential to reduce COE by up to 18% when compared with a permanent magnet direct drive 5MW baseline machine, resulting in a potential COE of 0.075 $/kWh. Finally, a top-level commercialization plan has been proposed to enable this technology to be transitioned to full volume production. The main body of this report will present the design processes employed and the main findings and conclusions.

Small windturbines are typically used for the remote or rural areas of the world including: a village in Chile; a cabin dweller in the U.S.; a farmer who wants to water his crop; or a utility company that wants to use distributed generation to help defer building new transmission lines and distribution facilities. Small windturbines can be used for powering communities, businesses, homes, and miscellaneous equipment to support unattended operation. This paper covers the U.S. Department of Energy/National Renewable Energy Laboratory Small WindTurbine project, its specifications, its applications, the subcontractors and their small windturbines concepts. 4 refs., 4 figs.

IntroductionIntroduction The use of small scale vertical axis windturbinesThe use of small scale vertical axis windturbines (VAWT) is being studied at McMaster University using(VAWT) is being studied at McMaster University using a prototype windturbine provided bya prototype windturbine provided

This research aims to have an impact towards a sustainable energy supply. In wind power generation losses occur at tip speed ratios which the rotor was not designed for. Since the ideal blade shape changes nonlinearly with ...

This report presents results of a comprehensive wind and windturbine measurement program: the Clayton, New Mexico, vertical plane array/MOD-OA project. In this experiment, the turbulent wind was measured for a large array of fixed anemometers located two blade diameters upwind of a 200-kW horizontal-axis windturbine (HAWT). Simultaneously, key windturbine response parameters were also measured. The first of two major objectives of this experiment was to determine the turbulent wind, rotationally sampled to emulate the motion of the windturbine blade, for the range of different wind speeds and stability classes actually experienced by the windturbine. The second major objective was to correlate this rotationally sampled wind with the windturbine blade stress and power, in order to assess the usefulness of the wind measurements for windturbine loads testing a prediction. Time series of rotationally sampled winds and windturbine blade bending moments and power were converted to frequency spectra using Fourier transform techniques. These spectra were used as the basis for both qualitative and quantitative comparisons among the various cases. A quantitative comparison between the rotationally sampled wind input and blade bending response was made, using the Fourier spectra to estimate the blade transfer function. These transfer functions were then used to calculate an approximate damping coefficient for the MOD-OA fiberglass blade.

High operation and maintenance costs still hamper the development of the wind industry despite its quick growth worldwide. To reduce unscheduled downtime and avoid catastrophic failures of windturbines and their components have been and will be crucial to further raise the competitiveness of wind power. Condition monitoring is one of the key tools for achieving such a goal. To enhance the research and development of advanced condition monitoring techniques dedicated to windturbines, we present an overview of windturbine condition monitoring, discuss current practices, point out existing challenges, and suggest possible solutions.

NREL researchers are supporting offshore wind power development with computer models that allow detailed analyses of both fixed and floating offshore windturbines. While existing computer-aided engineering (CAE) models can simulate the conditions and stresses that a land-based windturbine experiences over its lifetime, offshore turbines require the additional considerations of variations in water depth, soil type, and wind and wave severity, which also necessitate the use of a variety of support-structure types. NREL's core wind CAE tool, FAST, models the additional effects of incident waves, sea currents, and the foundation dynamics of the support structures.

The study presents a method and application of risk assessment methodology for turbinerotor fatigue failure using probabilistic ultrasonic nondestructive evaluations. A rigorous probabilistic modeling for ultrasonic flaw sizing is developed by incorporating the model-assisted probability of detection, and the probability density function (PDF) of the actual flaw size is derived. Two general scenarios, namely the ultrasonic inspection with an identified flaw indication and the ultrasonic inspection without flaw indication, are considered in the derivation. To perform estimations for fatigue reliability and remaining useful life, uncertainties from ultrasonic flaw sizing and fatigue model parameters are systematically included and quantified. The model parameter PDF is estimated using Bayesian parameter estimation and actual fatigue testing data. The overall method is demonstrated using a realistic application of steam turbinerotor, and the risk analysis under given safety criteria is provided to support maintenance planning.

An axial seal assembly is provided at the interface between adjacent wheels and spacers of a gas turbinerotor and disposed about tubes passing through openings in the rotor adjacent the rotor rim and carrying a thermal medium. Each seal assembly includes a support bushing for supporting a land of the thermal medium carrying tube, an axially registering seat bushing disposed in the opposed opening and a frustoconical seal between the seal bushing and seat. The seal bushing includes a radial flange having an annular recess for retaining the outer diameter edge of the seal, while the seat bushing has an axially facing annular surface forming a seat for engagement by the inner diameter edge of the seal.

Induction generators have been used since the early development of utility-scale windturbine generation. An induction generator is the generator of choice because of its ruggedness, and low cost. With an induction generator, the operating speed of the windturbine is limited to a narrow range (almost constant speed). Dual- speed operation can be accomplished by using an induction generator with two different sets of winding configurations or by using two induction generators with two different rated speeds. With single- speed operation, the windturbine operates at different power coefficients (Cp) as the wind speed varies. The operation at maximum Cp can occur only at a single wind speed. However, if the wind speed varies across a wider range, the operating Cp will vary significantly. Dual-speed operation has the advantage of enabling the windturbine to operate at near maximum Cp over a wider range of wind-speeds. Thus, annual energy production can be increased. The dual-speed mode may generate less energy than a variable-speed mode; nevertheless, it offers an alternative to capture more energy than single-speed operation. In this paper, dual-speed operation of a windturbine will be investigated. One type of control algorithm for dual- speed operation is proposed. Results from a dynamic simulation will be presented to show how the control algorithm works and how power, current and torque of the system vary as the windturbine is exposed to varying wind speeds.

A windturbine capable of driving multiple electric generators having a ring or shroud structure for reducing blade root bending moments, hub loads, blade fastener loads and pitch bearing loads. The shroud may further incorporate a ring gear for driving an electric generator. In one embodiment, the electric generator may be cantilevered from the nacelle such that the gear on the generator drive shaft is contacted by the ring gear of the shroud. The shroud also provides protection for the gearing and aids in preventing gear lubricant contamination.

Infrasound, the Ear and WindTurbines Alec N. Salt, Ph.D. Department of Otolaryngology there happens to be a castle nearby). #12;Windturbines haveWindturbines have been getting biggerbeen getting MegaWatts(MW) Total Installed Change by year 3% of US Energy Needs Windturbines are "green" and areWind

windturbines with rotor diameters in the order of 100 meters, the influence of upstream turbine wakes codes for windturbines utilize aerodynamics based on BEM methods, see [1, 2]. For modern large scale. Sørensen Wind Energy Department, Risø National Laboratory & Department of Civil Engineering, Aalborg

This report examines the complex interactions between atmospheric stability and turbine-induced wakes on downwind turbinewind speed and power production at a West Coast North American multi-MW wind farm. Wakes are generated when the upwind flow field is distorted by the mechanical movement of the windturbine blades. This has two consequences for downwind turbines: (1) the downwind turbine encounters wind flows with reduced velocity and (2) the downwind turbine encounters increased turbulence across multiple length scales via mechanical turbulence production by the upwind turbine. This increase in turbulence on top of ambient levels may increase aerodynamic fatigue loads on the blades and reduce the lifetime of turbine component parts. Furthermore, ambient atmospheric conditions, including atmospheric stability, i.e., thermal stratification in the lower boundary layer, play an important role in wake dissipation. Higher levels of ambient turbulence (i.e., a convective or unstable boundary layer) lead to higher turbulent mixing in the wake and a faster recovery in the velocity flow field downwind of a turbine. Lower levels of ambient turbulence, as in a stable boundary layer, will lead to more persistent wakes. The wake of a windturbine can be divided into two regions: the near wake and far wake, as illustrated in Figure 1. The near wake is formed when the turbine structure alters the shape of the flow field and usually persists one rotor diameter (D) downstream. The difference between the air inside and outside of the near wake results in a shear layer. This shear layer thickens as it moves downstream and forms turbulent eddies of multiple length scales. As the wake travels downstream, it expands depending on the level of ambient turbulence and meanders (i.e., travels in non-uniform path). Schepers estimates that the wake is fully expanded at a distance of 2.25 D and the far wake region begins at 2-5 D downstream. The actual distance traveled before the wake recovers to its inflow velocity is dependent on the amount ambient turbulence, the amount of wind shear, and topographical and structural effects. The maximum velocity deficit is estimated to occur at 1-2 D but can be longer under low levels of ambient turbulence. Our understanding of turbine wakes comes from wind tunnel experiments, field experiments, numerical simulations, and from studies utilizing both experimental and modeling methods. It is well documented that downwind turbines in multi-Megawatt wind farms often produce less power than upwind turbine rows. These wake-induced power losses have been estimated from 5% to up to 40% depending on the turbine operating settings (e.g., thrust coefficient), number of turbine rows, turbine size (e.g., rotor diameter and hub-height), wind farm terrain, and atmospheric flow conditions (e.g., ambient wind speed, turbulence, and atmospheric stability). Early work by Elliott and Cadogan suggested that power data for different turbulent conditions be segregated to distinguish the effects of turbulence on wind farm power production. This may be especially important for downwind turbines within wind farms, as chaotic and turbulent wake flows increase stress on downstream turbines. Impacts of stability on turbine wakes and power production have been examined for a flat terrain, moderate size (43 turbines) wind farm in Minnesota and for an offshore, 80 turbinewind farm off the coast of Denmark. Conzemius found it difficult to distinguish wakes (i.e., downwind velocity deficits) when the atmosphere was convective as large amounts of scatter were present in the turbine nacelle wind speed data. This suggested that high levels of turbulence broke-up the wake via large buoyancy effects, which are generally on the order of 1 km in size. On the other hand, they found pronounced wake effects when the atmosphere was very stable and turbulence was either suppressed or the length scale was reduced as turbulence in this case was mechanically produced (i.e., friction forces). This led to larger reductions at downwind turbines and maximum ve

The development of technologically advanced, high-efficiency windturbines continues to be a high-priority activity of the US wind industry. The National Renewable Energy Laboratory (formerly the Solar Energy Research Institute), sponsored by the US Department of Energy (DOE), has initiated the Advanced WindTurbine Program to assist the wind industry in the development of a new class of advanced windturbines. The initial phase of the program focused on developing conceptual designs for near-term and advanced turbines. The goal of the second phase of this program is to use the experience gained over the last decade of turbine design and operation combined with the latest existing design tools to develop a turbine that will produce energy at $0.05 per kilowatt-hour (kWh) in a 5.8-m/s (13-mph) wind site. Three contracts have been awarded, and two more are under negotiation in the second phase. The third phase of the program will use new innovations and state-of-the-art windturbine design technology to produce a turbine that will generate energy at $0.04/kWh in a 5.8-m/s wind site. Details of the third phase will be announced in early 1993.

This project was established to help reduce the barriers of wind energy expansion by providing independent testing results for small windturbines. Five turbines were tested at the National Wind Technology Center (NWTC) at the National Renewable Energy Laboratory (NREL) as a part of round one of this project. Duration testing is one of up to five tests that may be performed on the turbines, including power performance, safety and function, noise, and power quality. Test results will provide manufacturers with reports that can be used to fulfill part of the requirements for small windturbine certification. The test equipment included a grid-connected Ventera Energy Corporation VT10 windturbine mounted on an 18.3-m (60-ft) self-supporting lattice tower manufactured by Rohn.

This report surveys the analysis and tests performed at Washington University in St. Louis, Missouri, on a horizontal-axis, two-laded windturbine with teeter hub. The introduction is a brief account of results obtained during the 5-year period ending December 1985. The wind tunnel model and the test turbine (7.6 m [25 ft.] in diameter) at Washington University`s Tyson Research Center had a 67{degree} delta-three angle of the teeter axis. The introduction explains why this configuration was selected and named the passive cycle pitch (PCP) windturbine. Through the analysis was not limited to the PCP rotor, all tests, including those done from 1986 to 1994, wee conducted with the same teetered windrotor. The blades are rather stiff and have only a small elastic coning angle and no precone.

Taking a bottom-up approach, this report examines seven primary drivers of windturbine prices in the United States, with the goal of estimating the degree to which each contributed to the doubling in turbine prices from 2002 through 2008, as well as the subsequent decline in prices through 2010 (our analysis does not extend into 2011 because several of these drivers are best gauged on a full-year basis due to seasonality issues). The first four of these drivers can be considered, at least to some degree, endogenous influences  i.e., those that are largely within the control of the wind industry  and include changes in: 1) Labor costs, which have historically risen during times of tight turbine supply; 2) Warranty provisions, which reflect technology performance and reliability, and are most often capitalized in turbine prices; 3) Turbine manufacturer profitability, which can impact turbine prices independently of costs; and 4) Turbine design, which for the purpose of this analysis is principally manifested through increased turbine size. The other three drivers analyzed in this study can be considered exogenous influences, in that they can impact windturbine costs but fall mostly outside of the direct control of the wind industry. These exogenous drivers include changes in: 5) Raw materials prices, which affect the cost of inputs to the manufacturing process; 6) Energy prices, which impact the cost of manufacturing and transporting turbines; and 7) Foreign exchange rates, which can impact the dollar amount paid for turbines and components imported into the United States.

By the end of 2003, the total installed wind farm capacity in the Electric Reliability Council of Texas (ERCOT) system was approximately 1 gigawatt (GW) and the total in the United States was about 5 GW. As the number of windturbines installed throughout the United States increases, there is a greater need for dynamic windturbine generator models that can properly model entire power systems for different types of analysis. This paper describes the ERCOT dynamic models and simulations of a simple network with different types of windturbine models currently available.

CgWind is a high-fidelity large eddy simulation (LES) tool designed to meet the modeling needs of windturbine and wind park engineers. This tool combines several advanced computational technologies in order to model accurately the complex and dynamic nature of wind energy applications. The composite grid approach provides high-quality structured grids for the efficient implementation of high-order accurate discretizations of the incompressible Navier-Stokes equations. Composite grids also provide a natural mechanism for modeling bodies in relative motion and complex geometry. Advanced algorithms such as matrix-free multigrid, compact discretizations and approximate factorization will allow CgWind to perform highly resolved calculations efficiently on a wide class of computing resources. Also in development are nonlinear LES subgrid-scale models required to simulate the many interacting scales present in large windturbine applications. This paper outlines our approach, the current status of CgWind and future development plans.

design applied to a horizontal windturbine, functioning in the above rated wind speeds area. The turbines chosen for study in this paper are variable speed windturbines and the main focus will fall. The controller presented here, is a robust digital controller which aims to regulate the windturbinerotor speed

The US wind Industry has experienced remarkable growth since the turn of the century. At the same time, the physical size and electrical generation capabilities of windturbines has also experienced remarkable growth. As the market continues to expand, and as wind generation continues to gain a significant share of the generation portfolio, the reliability of windturbine technology becomes increasingly important. This report addresses how operations and maintenance costs are related to unreliability - that is the failures experienced by systems and components. Reliability tools are demonstrated, data needed to understand and catalog failure events is described, and practical windturbine reliability models are illustrated, including preliminary results. This report also presents a continuing process of how to proceed with controlling industry requirements, needs, and expectations related to Reliability, Availability, Maintainability, and Safety. A simply stated goal of this process is to better understand and to improve the operable reliability of windturbine installations.

In 1992, the Electric Power Research Institute (EPRI) and the US Department of Energy (DOE) initiated the Utility WindTurbine Performance Verification Program (TVP). This paper provides an overview of the TVP, its purpose and goals, and the participating utility projects. Improved technology has significantly reduced the cost of energy from windturbines since the early 1980s. In 1992, turbines were producing electricity for about $0.07--$0.09/kilowatt-hour (kWh) (at 7 m/s [16 mph sites]), compared with more than $0.30/kWh in 1980. Further technology improvements were expected to lower the cost of energy from windturbines to $0.05/kWh. More than 17,000 windturbines, totaling more than 1,500 MW capacity, were installed in the US, primarily in California and Hawaii. The better wind plants had availabilities above 95%, capacity factors exceeding 30%, and operation and maintenance costs of $0.01/kWh. However, despite improving technology, EPRI and DOE recognized that utility use of windturbines was still largely limited to turbines installed in California and Hawaii during the 1980s. Wind resource assessments showed that other regions of the US, particularly the Midwest, had abundant wind resources. EPRI and DOE sought to provide a bridge from utility-grade turbine development programs under way to commercial purchases of the windturbines. The TVP was developed to allow utilities to build and operate enough candidate turbines to gain statistically significant operating and maintenance data.

This paper describes a recent study to investigate the applicability of a horizontal-axis windturbine (HAWT) structural dynamics and unsteady aerodynamics analysis program (FAST and AeroDyn respectively) to modeling the forces on marine hydrokinetic (MHK) turbines. This paper summarizes the added mass model that has been added to AeroDyn. The added mass model only includes flow acceleration perpendicular to the rotor disc, and ignores added mass forces caused by blade deflection. A model of the National Renewable Energy Laboratory's (NREL) Unsteady Aerodynamics Experiment (UAE) Phase VI windturbine was analyzed using FAST and AeroDyn with sea water conditions and the new added mass model. The results of this analysis exhibited a 3.6% change in thrust for a rapid pitch case and a slight change in amplitude and phase of thrust for a case with 30{sup o} of yaw.

This paper describes a recent study to investigate the applicability of a horizontal-axis windturbine (HAWT) structural dynamics and unsteady aerodynamics analysis program (FAST and AeroDyn respectively) to modeling the forces on marine hydrokinetic (MHK) turbines. It summarizes the added mass model that has been added to AeroDyn. The added mass model only includes flow acceleration perpendicular to the rotor disc, and ignores added mass forces caused by blade deflection. A model of the National Renewable Energy Laboratory's (NREL) Unsteady Aerodynamics Experiment (UAE) Phase VI windturbine was analyzed using FAST and AeroDyn with sea water conditions and the new added mass model. The results of this analysis exhibited a 3.6% change in thrust for a rapid pitch case and a slight change in amplitude and phase of thrust for a case with 30 degrees of yaw.

PHYSICAL REVIEW E 88, 042146 (2013) Uncovering windturbine properties through two, such as the rated speed of the windturbine or the descriptive wind speed statistics, can be related to the equations describing the evolution of power production and wind speed at single windturbines. DOI: 10

An axial bore tube assembly for a turbine is provided to supply cooling steam to hot gas components of the turbine wheels and return the spent cooling steam. A pair of inner and outer tubes define a steam supply passage concentric about an inner return passage. The forward ends of the tubes communicate with an end cap assembly having sets of peripheral holes communicating with first and second sets of radial tubes whereby cooling steam from the concentric passage is supplied through the end cap holes to radial tubes for cooling the buckets and return steam from the buckets is provided through the second set of radial tubes through a second set of openings of the end cap into the coaxial return passage. A radial-to-axial flow transitioning device, including anti-swirling vanes is provided in the end cap. A strut ring adjacent the aft end of the bore tube assembly permits axial and radial thermal expansion of the inner tube relative to the outer tube.

This test was conducted as part of the U.S. Department of Energy's (DOE) Independent Testing project. This project was established to help reduce the barriers of wind energy expansion by providing independent testing results for small turbines. Three turbines where selected for testing at the National Wind Technology Center (NWTC) as a part of round two of the Small WindTurbine Independent Testing project. Duration testing is one of up to 5 tests that may be performed on the turbines. Other tests include power performance, safety and function, noise, and power quality. The results of the testing will provide the manufacturers with reports that may be used for small windturbine certification.

This test was conducted as part of the U.S. Department of Energy's (DOE) Independent Testing project. This project was established to help reduce the barriers of wind energy expansion by providing independent testing results for small turbines. Three turbines where selected for testing at the National Wind Technology Center (NWTC) as a part of round two of the Small WindTurbine Independent Testing project. Safety and Function testing is one of up to 5 tests that may be performed on the turbines. Other tests include power performance, duration, noise, and power quality. The results of the testing will provide the manufacturers with reports that may be used for small windturbine certification.

The WindTurbine Drivetrain Test Facility (WTDTF) is a state-of-the-art industrial facility used for testing windturbine drivetrains and generators. Large power output windturbines are primarily installed for off-shore wind power generation. The facility includes two test bays: one to accommodate turbine nacelles up to 7.5 MW and one for nacelles up to 15 MW. For each test bay, an independent data acquisition system (DAS) records signals from various sensors required for turbine testing. These signals include resistance temperature devices, current and voltage sensors, bridge/strain gauge transducers, charge amplifiers, and accelerometers. Each WTDTF DAS also interfaces with the drivetrain load applicator control system, electrical grid monitoring system and vibration analysis system.

The disclosed invention is utilized for mounting a windturbine and blade assembly on the upper end of a windturbine tower. The invention generally includes a frame or truss that is pivotally secured to the top bay assembly of the tower. A transverse beam is connected to the frame or truss and extends fore of the tower when the frame or truss is in a first position and generally above the tower when in a second position. When in the first position, a windturbine or blade assembly can be hoisted to the top of the tower. The windturbine or blade assembly is then moved into position for mounting to the tower as the frame or truss is pivoted to a second position. When the turbine and blade assembly are secured to the tower, the frame or truss is disconnected from the tower and lowered to the ground.

This paper presents some analysis results for incipient crack detection in a 9-meter CX-100 windturbine blade that underwent fatigue loading to failure. The blade was manufactured to standard specifications, and it underwent harmonic excitation at its first resonance using a hydraulically-actuated excitation system until reaching catastrophic failure. This work investigates the ability of an ultrasonic guided wave approach to detect incipient damage prior to the surfacing of a visible, catastrophic crack. The blade was instrumented with piezoelectric transducers, which were used in an active, pitchcatch mode with guided waves over a range of excitation frequencies. The performance results in detecting incipient crack formation in the fiberglass skin of the blade is assessed over the range of frequencies in order to determine the point at which the incipient crack became detectable. Higher excitation frequencies provide consistent results for paths along the rotor blade's carbon fiber spar cap, but performance falls off with increasing excitation frequencies for paths off of the spar cap. Lower excitation frequencies provide more consistent performance across all sensor paths.

Design, Analysis, and Learning Control of a Fully Actuated Micro WindTurbine J. Zico Kolter of renewable energy, and improvements to windturbine design and control can have a significant impact a actuated micro windturbine intended for research purposes. While most academic work on windturbine

A High-Order Sliding Mode Observer for Sensorless Control ofDFIG-Based WindTurbines Mohamed control of a doubly-fed induction generator (DFIG) based windturbine. The sensorless control scheme (generator and turbine). Simulations using the windturbine simulator FAST on a 1.5- MW three-blade wind

The Potential Health Impact of WindTurbines Chief Medical Officer of Health (CMOH) Report May 2010 on the potential health impact of windturbines in collaboration and consultation with a technical working group is available on the potential health impacts of windturbines? Â· What is the relationship between windturbine

The development of technologically advanced, higher efficiency windturbines continues to be a high priority activity of the US wind industry. The United States Department of Energy (DOE) is conducting and sponsoring a range of programs aimed at assisting the wind industry with system design, development, and testing. The overall goal is to develop systems that can compete with conventional electric generation for $.05/kWh at 5.8 m/s (13 mph sites) by the mid-1990s and with fossil-fuel-based generators for $.04/kWh at 5.8 m/s sites by the year 2000. These goals will be achieved through several programs. The Value Engineered Turbine Program will promote the rapid development of US capability to manufacture windturbines with known and well documented records of performance, cost, and reliability, to take advantage of near-term market opportunities. The Advanced WindTurbine Program will assist US industry to develop and integrate innovative technologies into utility-grade windturbines for the near-term (mid 1990s) and to develop a new generation of turbines for the year 2000. The collaborative Electric Power Research Institute (EPRI)/DOE Utility WindTurbine Performance Verification Program will deploy and evaluate commercial-prototype windturbines in typical utility operating environments, to provide a bridge between development programs currently underway and commercial purchases of utility-grade windturbines. A number of collaborative efforts also will help develop a range of small systems optimized to work in a diesel hybrid environment to provide electricity for smaller non-grid-connected applications.

A wind generator having removable change-out bearings includes a rotor and a stator, locking bolts configured to lock the rotor and stator, a removable bearing sub-assembly having at least one shrunk-on bearing installed, and removable mounting bolts configured to engage the bearing sub-assembly and to allow the removable bearing sub-assembly to be removed when the removable mounting bolts are removed.

A wind generator having removable change-out bearings includes a rotor and a stator, locking bolts configured to lock the rotor and stator, a removable bearing sub-assembly having at least one shrunk-on bearing installed, and removable mounting bolts configured to engage the bearing sub-assembly and to allow the removable bearing sub-assembly to be removed when the removable mounting bolts are removed.

Assessing Novel Foundation Options for Offshore WindTurbines B.W. Byrne, BE(Hons), BCom, MA, DPhil G.T. Houlsby, MA, DSc, FREng, FICE Oxford University, UK SYNOPSIS Offshore wind farms, and of these wind power is the only one to be exploited on a commercial scale at present. Three major offshore

Sandia National Laboratories has developed a family of airfoils specifically designed for use in the equatorial portion of a Vertical-Axis WindTurbine (VAWT) blade. An airfoil of that family has been incorporated into the rotor blades of the DOE/Sandia 34-m diameter VAWT Test Bed. The airfoil and rotor design process is reviewed. Comparisons with data recently acquired from flow visualization tests and from the DOE/Sandia 34-m diameter VAWT Test Bed illustrate the success that was achieved in the design. The economic optimization model used in the design is described and used to evaluate the effect of modifications to the current Test Bed blade. 1 tab., 11 figs., 13 refs.

Impact of DFIG windturbines on transient stability of power systems Â­ a review Authors Na Abstract of wind farms are using variable speed windturbines equipped with doubly-fed induction generators (DFIG) due to their advantages over other windturbine generators. Therefore, the analysis of wind power

This presentation was given at the 2011 WindTurbine Reliability Workshop sponsored by Sandia National Laboratories in Albuquerque, NM on August 2-3, 2011. It discusses work for the Gearbox Reliability Collaborative including downtime caused by turbine subsystems, annual failure frequency of turbine subsystems, cost benefits of condition monitoring (CM), the Gearbox Reliability Collaborative's condition monitoring approach and rationale, test setup, and results and observations.

An aeroelastic stability analysis has been developed for predicting flutter instabilities on vertical axis windturbines. The analytical model and mathematical formulation of the problem are described as well as the physical mechanism that creates flutter in Darrieus turbines. Theoretical results are compared with measured experimental data from flutter tests of the Sandia 2 Meter turbine. Based on this comparison, the analysis appears to be an adequate design evaluation tool.

Ultra-High Performance Concrete (UHPC) has proven an asset for bridge design as it significantly reduces costs. However, UHPC has not been applied yet to windturbine technology. Design codes do not propose any recommendations ...

There are many problems associated with small windturbines, such as small Reynolds number and poor starting performance, that make them much more expensive than the large ones per unit power. New technologies are needed to improve the quality...

There are many problems associated with small windturbines, such as small Reynolds number and poor starting performance, that make them much more expensive than the large ones per unit power. New technologies are needed to improve the quality...

This thesis describes four novel superconducting machine concepts, in the pursuit of finding a suitable design for large offshore windturbines. The designs should be reliable, modular and light-weight. The main novelty ...

ABSTRACT Howard Graham, Master of Arts American Studies, July 2008 University of Kansas This study examines the political and social controversy surrounding the proposed introduction of industrial scale windturbines, roughly, those over 120 feet...

This research study developed basic dynamic models that can be used to accurately predict the response behavior of a near-shore windturbine structure with monopile, suction caisson, or gravity-based foundation systems. The marine soil conditions...

The author presents a concept for a vertical axis windturbine that utilizes each blade's entire rotational cycle for power generation. Each blade has its own vertical axis of rotation and is constrained to rotate at the ...

The proposed DOE/Sandia Scaled Wind Farm Technology Facility (SWiFT) hosted by Texas Tech University at Reese Technology Center in Lubbock, TX, will provide a facility for experimental study of turbine-turbine interaction and complex wind farm aerodynamics. This document surveys the current status of windturbine wake and turbine-turbine interaction research, identifying knowledge and data gaps that the proposed test site can potentially fill. A number of turbine layouts is proposed, allowing for up to ten turbines at the site.

Modern windturbines are complex, highly-coupled systems. The dynamic interaction between various components is especially pronounced for multi-megawatt windturbines. As a result, design process is generally split in several phases. First step consists of creating a global aero-elastic model that includes essential dynamics of structural components using the minimum-possible number of degrees of freedom (d.o.f.). The most important simplifications concern drivetrain and rotor-nacelle assembly (RNA). This approach has been shown valid for several windturbine configurations. Nevertheless, with increasing size of windturbines, any simplified design approach must be validated. The present work deals with the comparison and validation of the two modeling approaches for directdrive offshore windturbines. ARNA/drivetrain model idealized as collection of lumped masses and springs is compared to a detailed Finite Element Method (FEM) based model. The comparison between models focuses on dynamic loads concerning drivetrain system. The comparison is performed in several operational conditions in order to explore the range of validity of the simplified model. Finally, the paper proposes a numerical-based workflow to assess the validity of simplified models of RNA/drivetrain in an aero-elastic global WT model.

The fluid dynamics video considers an array of two NREL 5-MW turbines separated by seven rotor diameters in a neutral atmospheric boundary layer (ABL). The neutral atmospheric boundary-layer flow data were obtained from a precursor ABL simulation using a Large-Eddy Simulation (LES) framework within OpenFOAM. The mean wind speed at hub height is 8m/s, and the surface roughness is 0.2m. The actuator line method (ALM) is used to model the windturbine blades by means of body forces added to the momentum equation. The fluid dynamics video shows the root and tip vortices emanating from the blades from various viewpoints. The vortices become unstable and break down into large-scale turbulent structures. As the wakes of the windturbines advect further downstream, smaller-scale turbulence is generated. It is apparent that vortices generated by the blades of the downstream windturbine break down faster due to increased turbulence levels generated by the wake of the upstream windturbine.

Windturbine blades must undergo strength and fatigue testing in order to be rated and marketed appropriately. Presently, windturbine blades are fatigue-tested in the flapwise direction and in the edgewise direction independently. This testing involves placing the blades through 1 to 10 million or more load or fatigue cycles, which may take 3 to 12 months or more to complete for each tested direction. There is a need for blade testing techniques that are less expensive to use and require...

IDENTIFICATION OF AIRFOIL CHARACTERISTICS FOR OPTIMUM WINDTURBINE PERFORMANCE A Thesis by LEONARD SCOTT MILLER Submitted to the Graduate College of Texas ASM University in partial fulfillment of the requirement for the degree of MASTER... OF SCIENCE December 1983 Major Subject: Aerospace Engineering IDENTIFICATION OF AIRFOIL CHARACTERISTICS FOR OPTIMUM WINDTURBINE PERFORMANCE A Thesis by LEONARD SCOTT MILLER Approved as to Style and Content by: Dr. S. J. Miley (Chairm of Committee...

MPC for Wind Power Gradients -- Utilizing Forecasts, Rotor Inertia, and Central Energy Storage define an extremely low power output gradient and demonstrate how decentralized energy storage conservative bids on the power market. Energy storage strikes the major problems of wind power and joining

RIS0-M-2242 ANALYSIS OF DATA FROM THE GEDSER WINDTURBINE 1977-1979 P. Lundsager, S. Frandsen, C on the data from the Gedser windturbine measurements, made during 1977 to 1979. The report contains chap turbine with modern Danish, Swedish and American experimental windturbines, based on published data. UDC

Variable-speed, horizontal axis windturbines use blade-pitch control to meet specified objectives for three regions of operation. This paper focuses on controller design for the constant power production regime. A simple, rigid, non-linear turbine model was used to systematically perform trade-off studies between two performance metrics. Minimization of both the deviation of the rotor speed from the desired speed and the motion of the actuator is desired. The robust nature of the proportional-integral-derivative (PID) controller is illustrated, and optimal operating conditions are determined. Because numerous simulation runs may be completed in a short time, the relationship of the two opposing metrics is easily visualized. 2 refs., 9 figs.

at the Horns Rev offshore wind farm. The influence of atmospheric stability on the surface layer wind shear of offshore wind farms in the coming years. In contrast with the situation over land, the knowledge turbine manufacturers and wind farm developers, although the offshore environment represents other

This brief paper discusses factors that must be considered when defining the {open_quotes}normal{close_quotes} (as opposed to {open_quotes}extreme{close_quotes}) loading conditions seen in windturbines operating within a wind park environment. The author defines the {open_quotes}normal{close_quotes} conditions to include fatigue damage accumulation as a result of: (1) start/stop cycles, (2) emergency shutdowns, and (3) the turbulence environment associated with site and turbine location. He also interprets {open_quotes}extreme{close_quotes} loading conditions to include those events that can challenge the survivability of the turbine.

This brief paper discusses factors that must be considered when defining the [open quotes]normal[close quotes] (as opposed to [open quotes]extreme[close quotes]) loading conditions seen in windturbines operating within a wind park environment. The author defines the [open quotes]normal[close quotes] conditions to include fatigue damage accumulation as a result of: (1) start/stop cycles, (2) emergency shutdowns, and (3) the turbulence environment associated with site and turbine location. He also interprets [open quotes]extreme[close quotes] loading conditions to include those events that can challenge the survivability of the turbine.

This report examines the accuracy of measurements that rely on Doppler LIDAR systems to determine their applicability to windturbine feed-forward control systems and discusses feed-forward control system designs that use preview wind measurements. Light Detection and Ranging (LIDAR) systems are able to measure the speed of incoming wind before it interacts with a windturbinerotor. These preview wind measurements can be used in feed-forward control systems designed to reduce turbine loads. However, the degree to which such preview-based control techniques can reduce loads by reacting to turbulence depends on how accurately the incoming wind field can be measured. The first half of this report examines the accuracy of different measurement scenarios that rely on coherent continuous-wave or pulsed Doppler LIDAR systems to determine their applicability to feed-forward control. In particular, the impacts of measurement range and angular offset from the wind direction are studied for various wind conditions. A realistic case involving a scanning LIDAR unit mounted in the spinner of a windturbine is studied in depth with emphasis on choices for scan radius and preview distance. The effects of turbulence parameters on measurement accuracy are studied as well. Continuous-wave and pulsed LIDAR models based on typical commercially available units were used in the studies present in this report. The second half of this report discusses feed-forward control system designs that use preview wind measurements. Combined feedback/feed-forward blade pitch control is compared to industry standard feedback control when simulated in realistic turbulent above-rated winds. The feed-forward controllers are designed to reduce fatigue loads, increasing turbine lifetime and therefore reducing the cost of energy. Three feed-forward designs are studied: non-causal series expansion, Preview Control, and optimized FIR filter. The input to the feed-forward controller is a measurement of incoming wind speeds that could be provided by LIDAR. Non-causal series expansion and Preview Control methods reduce blade root loads but increase tower bending in simulation results. The optimized FIR filter reduces loads overall, keeps pitch rates low, and maintains rotor speed regulation and power capture, while using imperfect wind measurements provided by the spinning continuous-wave LIDAR model.

This document reports the technical results of the Next Generation Turbine Development Project conducted by GE Wind Energy LLC. This project is jointly funded by GE and the U.S. Department of Energy's National Renewable Energy Laboratory.The goal of this project is for DOE to assist the U.S. wind industry in exploring new concepts and applications of cutting-edge technology in pursuit of the specific objective of developing a windturbine that can generate electricity at a levelized cost of energy of $0.025/kWh at sites with an average wind speed of 15 mph (at 10 m height).

In conjunction with the US Department of Energy and the National Renewable Energy Laboratory`s Advanced WindTurbine Program, the Atlantic Orient Corporation developed preliminary designs for the next generation of windturbines. These 50 kW and 350 kW turbines are based upon the concept of simplicity. By adhering to a design philosophy that emphasizes simplicity, we project that these turbines will produce energy at extremely competitive rates which will unlock the potential of wind energy domestically and internationally. The program consisted of three distinct phases. First, we evaluated the operational history of the Enertech 44 series windturbines. As a result of this evaluation, we developed, in the second phase, a preliminary design for a new 50 kW turbine for the near-term market. In the third phase, we took a clean-sheet-of-paper approach to designing a 350 kW turbine focused on the mid-1990s utility market that incorporated past experience and advanced technology.

Sparkær Blade Test Centre Fatigue tests of windturbine blades Flapwise fatigue tests of 3 blades wind load. By turning and oscillating the blade in the horzontal direction, an R-ratio of ­1 running at the Sparkær Centre Blade Test Facilities. Fatigue blade tests are performed in order

This presentation gives a brief overview to windturbine wake modeling, ranging from models used in the 1980s up to the present. The presentation shows the strengths and weaknesses of various models and discusses the needs of the wind energy industry and research sectors. Both power production and loads analysis are discussed.

sources. Wind energy is capable of providing 72 TW (TW = 10^12 W) of electric power, which is approximately four and half times the world energy consumption of 15.8 TW as reported in 2006. Since power output extracted from windturbines is proportional...

that wind is expected to come. Therefore it may be a good idea to consider a vertical-axis windturbine of the conventional windturbines use horizontal- axis configuration (see Fig. 1) and is aligned with the directionPROJECT 1: Project Title: Residential windturbine design Project Description: This project aims

Risø-R-1000(EN) Cost Optimization of WindTurbines for Large-scale Off-shore Wind Farms Peter contains a preliminary investigation of site specific design of off- shore windturbines for a large off using a design tool for windturbines that involve numerical optimization and aeroelastic calculations

phases of new windturbines. There are plans about offshore wind farms in many countries e.g. in northernRECYCLING AND REMOVAL OF OFFSHORE WINDTURBINES ­ AN INTERACTIVE METHOD FOR REDUCTION OF NEGATIVE and an analysis of future removal and recycling processes of offshore windturbines. The method is process

Mitigation of Fatigue Loads Using Individual Pitch Control of WindTurbines Based on FAST Yunqian University, China jiz@seu.edu.cn Abstract-With the increase of windturbine dimension and capacity, the windturbine structures are subjected to prominent loads and fatigue which would reduce the lifetime of wind

1 An Experimental Investigation on the Wake Interference of WindTurbines Sited Over Complex, 50011 An experimental study was conducted to investigate the interferences of windturbines sited over conducted in a large wind tunnel with of windturbine models sited over a flat terrain (baseline case

Set-point reconfiguration approach for the FTC of windturbines B. Boussaid C. Aubrun N system stability. The effectiveness of the proposed solution is illustrated by a windturbine example issue. Nowadays, windturbines which generate electrical energy from the wind energy are considered one

Multivariate analysis and prediction of windturbine response to varying wind field characteristics effects on windturbines are essential not only for designing, but also for cost-efficiently managing wind, Universitätsstr. 150, 44780 Bochum, GERMANY; email: hartus@inf.bi.rub.de ABSTRACT Site-specific wind field

Modern windturbines are fatigue critical machines that are typically used to produce electrical power from the wind. The materials used to construct these machines are subjected to a unique loading spectrum that contains several orders of magnitude more cycles than other fatigue critical structures, e.g., an airplane. To facilitate fatigue designs, a large database of material properties has been generated over the past several years that is specialized to materials typically used in windturbines. In this paper, I review these fatigue data. Major sections are devoted to the properties developed for wood, metals (primarily aluminum) and fiberglass. Special emphasis is placed on the fiberglass discussion because this material is current the material of choice for windturbine blades. The paper focuses on the data developed in the U.S., but cites European references that provide important insights.

Vibrations of a windturbine have a negative impact on its performance. Mitigating this undesirable impact requires knowledge of the relationship between the vibrations and other windturbine parameters that could be potentially modified. Three approaches for ranking the impact importance of measurable turbine parameters on the vibrations of the drive train and the tower are discussed. They include the predictor importance analysis, the global sensitivity analysis, and the correlation coefficient analysis versed in data mining and statistics. To decouple the impact of wind speed on the vibrations of the drive train and the tower, the analysis is performed on data sets with narrow speed ranges. Wavelet analysis is applied to filter noisy accelerometer data. To exclude the impact malfunctions on the vibration analysis, the data are analyzed in a frequency domain. Data-mining algorithms are used to build models with turbine parameters of interest as inputs, and the vibrations of drive train and tower as outputs. The performance of each model is thoroughly evaluated based on metrics widely used in the wind industry. The neural network algorithm outperforms other classifiers and is considered to be the most promising approach to study windturbine vibrations. ?DOI: 10.1115/1.4001461?

The purpose of this work is to develop a maximum power tracking control strategy for variable speed windturbine systems. Modern windturbine control systems are slow, and they depend on the design parameters of the turbine and use wind and/or rotor...

The purpose of this work is to develop a maximum power tracking control strategy for variable speed windturbine systems. Modern windturbine control systems are slow, and they depend on the design parameters of the turbine and use wind and/or rotor...

turbines off too early in high winds, or may risk severe damage to the rotors and blades by operating under Introduction Windturbines sit at the very bottom of the at- mospheric boundary layer, where winds are highly turbulent, shear events are intermittent, and land- atmosphere interactions may be strong. Turbine hub

The purpose of this work is to develop a maximum power tracking control strategy for variable speed windturbine systems. Modern windturbine control systems are slow, and they depend on the design parameters of the turbine and use wind and/or rotor...

The purpose of this work is to develop a maximum power tracking control strategy for variable speed windturbine systems. Modern windturbine control systems are slow, and they depend on the design parameters of the turbine and use wind and/or rotor...